Change Log: v2: Add CVE number inside the commit msg.
Naohiro Aota (1): btrfs: fix invalid mapping of extent xarray state
Qu Wenruo (1): btrfs: do not clear page dirty inside extent_write_locked_range()
fs/btrfs/extent_io.c | 18 ++++++++---------- 1 file changed, 8 insertions(+), 10 deletions(-)
From: Qu Wenruo wqu@suse.com
stable inclusion from stable-v6.6.45 commit ba4dedb71356638d8284e34724daca944be70368 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/IAHMJO CVE: CVE-2024-44972
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=t...
--------------------------------
[ Upstream commit 97713b1a2ced1e4a2a6c40045903797ebd44d7e0 ]
[BUG] For subpage + zoned case, the following workload can lead to rsv data leak at unmount time:
# mkfs.btrfs -f -s 4k $dev # mount $dev $mnt # fsstress -w -n 8 -d $mnt -s 1709539240 0/0: fiemap - no filename 0/1: copyrange read - no filename 0/2: write - no filename 0/3: rename - no source filename 0/4: creat f0 x:0 0 0 0/4: creat add id=0,parent=-1 0/5: writev f0[259 1 0 0 0 0] [778052,113,965] 0 0/6: ioctl(FIEMAP) f0[259 1 0 0 224 887097] [1294220,2291618343991484791,0x10000] -1 0/7: dwrite - xfsctl(XFS_IOC_DIOINFO) f0[259 1 0 0 224 887097] return 25, fallback to stat() 0/7: dwrite f0[259 1 0 0 224 887097] [696320,102400] 0 # umount $mnt
The dmesg includes the following rsv leak detection warning (all call trace skipped):
------------[ cut here ]------------ WARNING: CPU: 2 PID: 4528 at fs/btrfs/inode.c:8653 btrfs_destroy_inode+0x1e0/0x200 [btrfs] ---[ end trace 0000000000000000 ]--- ------------[ cut here ]------------ WARNING: CPU: 2 PID: 4528 at fs/btrfs/inode.c:8654 btrfs_destroy_inode+0x1a8/0x200 [btrfs] ---[ end trace 0000000000000000 ]--- ------------[ cut here ]------------ WARNING: CPU: 2 PID: 4528 at fs/btrfs/inode.c:8660 btrfs_destroy_inode+0x1a0/0x200 [btrfs] ---[ end trace 0000000000000000 ]--- BTRFS info (device sda): last unmount of filesystem 1b4abba9-de34-4f07-9e7f-157cf12a18d6 ------------[ cut here ]------------ WARNING: CPU: 3 PID: 4528 at fs/btrfs/block-group.c:4434 btrfs_free_block_groups+0x338/0x500 [btrfs] ---[ end trace 0000000000000000 ]--- BTRFS info (device sda): space_info DATA has 268218368 free, is not full BTRFS info (device sda): space_info total=268435456, used=204800, pinned=0, reserved=0, may_use=12288, readonly=0 zone_unusable=0 BTRFS info (device sda): global_block_rsv: size 0 reserved 0 BTRFS info (device sda): trans_block_rsv: size 0 reserved 0 BTRFS info (device sda): chunk_block_rsv: size 0 reserved 0 BTRFS info (device sda): delayed_block_rsv: size 0 reserved 0 BTRFS info (device sda): delayed_refs_rsv: size 0 reserved 0 ------------[ cut here ]------------ WARNING: CPU: 3 PID: 4528 at fs/btrfs/block-group.c:4434 btrfs_free_block_groups+0x338/0x500 [btrfs] ---[ end trace 0000000000000000 ]--- BTRFS info (device sda): space_info METADATA has 267796480 free, is not full BTRFS info (device sda): space_info total=268435456, used=131072, pinned=0, reserved=0, may_use=262144, readonly=0 zone_unusable=245760 BTRFS info (device sda): global_block_rsv: size 0 reserved 0 BTRFS info (device sda): trans_block_rsv: size 0 reserved 0 BTRFS info (device sda): chunk_block_rsv: size 0 reserved 0 BTRFS info (device sda): delayed_block_rsv: size 0 reserved 0 BTRFS info (device sda): delayed_refs_rsv: size 0 reserved 0
Above $dev is a tcmu-runner emulated zoned HDD, which has a max zone append size of 64K, and the system has 64K page size.
[CAUSE] I have added several trace_printk() to show the events (header skipped):
btrfs_dirty_pages: r/i=5/259 dirty start=774144 len=114688 btrfs_dirty_pages: r/i=5/259 dirty part of page=720896 off_in_page=53248 len_in_page=12288 btrfs_dirty_pages: r/i=5/259 dirty part of page=786432 off_in_page=0 len_in_page=65536 btrfs_dirty_pages: r/i=5/259 dirty part of page=851968 off_in_page=0 len_in_page=36864
The above lines show our buffered write has dirtied 3 pages of inode 259 of root 5:
704K 768K 832K 896K I |////I/////////////////I///////////| I 756K 868K
|///| is the dirtied range using subpage bitmaps. and 'I' is the page boundary.
Meanwhile all three pages (704K, 768K, 832K) have their PageDirty flag set.
btrfs_direct_write: r/i=5/259 start dio filepos=696320 len=102400
Then direct IO write starts, since the range [680K, 780K) covers the beginning part of the above dirty range, we need to writeback the two pages at 704K and 768K.
cow_file_range: r/i=5/259 add ordered extent filepos=774144 len=65536 extent_write_locked_range: r/i=5/259 locked page=720896 start=774144 len=65536
Now the above 2 lines show that we're writing back for dirty range [756K, 756K + 64K). We only writeback 64K because the zoned device has max zone append size as 64K.
extent_write_locked_range: r/i=5/259 clear dirty for page=786432
!!! The above line shows the root cause. !!!
We're calling clear_page_dirty_for_io() inside extent_write_locked_range(), for the page 768K. This is because extent_write_locked_range() can go beyond the current locked page, here we hit the page at 768K and clear its page dirt.
In fact this would lead to the desync between subpage dirty and page dirty flags. We have the page dirty flag cleared, but the subpage range [820K, 832K) is still dirty.
After the writeback of range [756K, 820K), the dirty flags look like this, as page 768K no longer has dirty flag set.
704K 768K 832K 896K I I | I/////////////| I 820K 868K
This means we will no longer writeback range [820K, 832K), thus the reserved data/metadata space would never be properly released.
extent_write_cache_pages: r/i=5/259 skip non-dirty folio=786432
Now even though we try to start writeback for page 768K, since the page is not dirty, we completely skip it at extent_write_cache_pages() time.
btrfs_direct_write: r/i=5/259 dio done filepos=696320 len=0
Now the direct IO finished.
cow_file_range: r/i=5/259 add ordered extent filepos=851968 len=36864 extent_write_locked_range: r/i=5/259 locked page=851968 start=851968 len=36864
Now we writeback the remaining dirty range, which is [832K, 868K). Causing the range [820K, 832K) never to be submitted, thus leaking the reserved space.
This bug only affects subpage and zoned case. For non-subpage and zoned case, we have exactly one sector for each page, thus no such partial dirty cases.
For subpage and non-zoned case, we never go into run_delalloc_cow(), and normally all the dirty subpage ranges would be properly submitted inside __extent_writepage_io().
[FIX] Just do not clear the page dirty at all inside extent_write_locked_range(). As __extent_writepage_io() would do a more accurate, subpage compatible clear for page and subpage dirty flags anyway.
Now the correct trace would look like this:
btrfs_dirty_pages: r/i=5/259 dirty start=774144 len=114688 btrfs_dirty_pages: r/i=5/259 dirty part of page=720896 off_in_page=53248 len_in_page=12288 btrfs_dirty_pages: r/i=5/259 dirty part of page=786432 off_in_page=0 len_in_page=65536 btrfs_dirty_pages: r/i=5/259 dirty part of page=851968 off_in_page=0 len_in_page=36864
The page dirty part is still the same 3 pages.
btrfs_direct_write: r/i=5/259 start dio filepos=696320 len=102400 cow_file_range: r/i=5/259 add ordered extent filepos=774144 len=65536 extent_write_locked_range: r/i=5/259 locked page=720896 start=774144 len=65536
And the writeback for the first 64K is still correct.
cow_file_range: r/i=5/259 add ordered extent filepos=839680 len=49152 extent_write_locked_range: r/i=5/259 locked page=786432 start=839680 len=49152
Now with the fix, we can properly writeback the range [820K, 832K), and properly release the reserved data/metadata space.
Reviewed-by: Johannes Thumshirn johannes.thumshirn@wdc.com Signed-off-by: Qu Wenruo wqu@suse.com Signed-off-by: David Sterba dsterba@suse.com Signed-off-by: Sasha Levin sashal@kernel.org Signed-off-by: Long Li leo.lilong@huawei.com Signed-off-by: Yifan Qiao qiaoyifan4@huawei.com --- fs/btrfs/extent_io.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-)
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c index 9fbffd84b16c..c6a95dfa59c8 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -2172,10 +2172,8 @@ void extent_write_locked_range(struct inode *inode, struct page *locked_page,
page = find_get_page(mapping, cur >> PAGE_SHIFT); ASSERT(PageLocked(page)); - if (pages_dirty && page != locked_page) { + if (pages_dirty && page != locked_page) ASSERT(PageDirty(page)); - clear_page_dirty_for_io(page); - }
ret = __extent_writepage_io(BTRFS_I(inode), page, &bio_ctrl, i_size, &nr);
From: Naohiro Aota naohiro.aota@wdc.com
mainline inclusion from mainline-v6.10-rc2 commit 6252690f7e1b173b86a4c27dfc046b351ab423e7 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/IAHMJO CVE: CVE-2024-44972
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...
--------------------------------
In __extent_writepage_io(), we call btrfs_set_range_writeback() -> folio_start_writeback(), which clears PAGECACHE_TAG_DIRTY mark from the mapping xarray if the folio is not dirty. This worked fine before commit 97713b1a2ced ("btrfs: do not clear page dirty inside extent_write_locked_range()").
After the commit, however, the folio is still dirty at this point, so the mapping DIRTY tag is not cleared anymore. Then, __extent_writepage_io() calls btrfs_folio_clear_dirty() to clear the folio's dirty flag. That results in the page being unlocked with a "strange" state. The page is not PageDirty, but the mapping tag is set as PAGECACHE_TAG_DIRTY.
This strange state looks like causing a hang with a call trace below when running fstests generic/091 on a null_blk device. It is waiting for a folio lock.
While I don't have an exact relation between this hang and the strange state, fixing the state also fixes the hang. And, that state is worth fixing anyway.
This commit reorders btrfs_folio_clear_dirty() and btrfs_set_range_writeback() in __extent_writepage_io(), so that the PAGECACHE_TAG_DIRTY tag is properly removed from the xarray.
[464.274] task:fsx state:D stack:0 pid:3034 tgid:3034 ppid:2853 flags:0x00004002 [464.286] Call Trace: [464.291] <TASK> [464.295] __schedule+0x10ed/0x6260 [464.301] ? __pfx___blk_flush_plug+0x10/0x10 [464.308] ? __submit_bio+0x37c/0x450 [464.314] ? __pfx___schedule+0x10/0x10 [464.321] ? lock_release+0x567/0x790 [464.327] ? __pfx_lock_acquire+0x10/0x10 [464.334] ? __pfx_lock_release+0x10/0x10 [464.340] ? __pfx_lock_acquire+0x10/0x10 [464.347] ? __pfx_lock_release+0x10/0x10 [464.353] ? do_raw_spin_lock+0x12e/0x270 [464.360] schedule+0xdf/0x3b0 [464.365] io_schedule+0x8f/0xf0 [464.371] folio_wait_bit_common+0x2ca/0x6d0 [464.378] ? folio_wait_bit_common+0x1cc/0x6d0 [464.385] ? __pfx_folio_wait_bit_common+0x10/0x10 [464.392] ? __pfx_filemap_get_folios_tag+0x10/0x10 [464.400] ? __pfx_wake_page_function+0x10/0x10 [464.407] ? __pfx___might_resched+0x10/0x10 [464.414] ? do_raw_spin_unlock+0x58/0x1f0 [464.420] extent_write_cache_pages+0xe49/0x1620 [btrfs] [464.428] ? lock_acquire+0x435/0x500 [464.435] ? __pfx_extent_write_cache_pages+0x10/0x10 [btrfs] [464.443] ? btrfs_do_write_iter+0x493/0x640 [btrfs] [464.451] ? orc_find.part.0+0x1d4/0x380 [464.457] ? __pfx_lock_release+0x10/0x10 [464.464] ? __pfx_lock_release+0x10/0x10 [464.471] ? btrfs_do_write_iter+0x493/0x640 [btrfs] [464.478] btrfs_writepages+0x1cc/0x460 [btrfs] [464.485] ? __pfx_btrfs_writepages+0x10/0x10 [btrfs] [464.493] ? is_bpf_text_address+0x6e/0x100 [464.500] ? kernel_text_address+0x145/0x160 [464.507] ? unwind_get_return_address+0x5e/0xa0 [464.514] ? arch_stack_walk+0xac/0x100 [464.521] do_writepages+0x176/0x780 [464.527] ? lock_release+0x567/0x790 [464.533] ? __pfx_do_writepages+0x10/0x10 [464.540] ? __pfx_lock_acquire+0x10/0x10 [464.546] ? __pfx_stack_trace_save+0x10/0x10 [464.553] ? do_raw_spin_lock+0x12e/0x270 [464.560] ? do_raw_spin_unlock+0x58/0x1f0 [464.566] ? _raw_spin_unlock+0x23/0x40 [464.573] ? wbc_attach_and_unlock_inode+0x3da/0x7d0 [464.580] filemap_fdatawrite_wbc+0x113/0x180 [464.587] ? prepare_pages.constprop.0+0x13c/0x5c0 [btrfs] [464.596] __filemap_fdatawrite_range+0xaf/0xf0 [464.603] ? __pfx___filemap_fdatawrite_range+0x10/0x10 [464.611] ? trace_irq_enable.constprop.0+0xce/0x110 [464.618] ? kasan_quarantine_put+0xd7/0x1e0 [464.625] btrfs_start_ordered_extent+0x46f/0x570 [btrfs] [464.633] ? __pfx_btrfs_start_ordered_extent+0x10/0x10 [btrfs] [464.642] ? __clear_extent_bit+0x2c0/0x9d0 [btrfs] [464.650] btrfs_lock_and_flush_ordered_range+0xc6/0x180 [btrfs] [464.659] ? __pfx_btrfs_lock_and_flush_ordered_range+0x10/0x10 [btrfs] [464.669] btrfs_read_folio+0x12a/0x1d0 [btrfs] [464.676] ? __pfx_btrfs_read_folio+0x10/0x10 [btrfs] [464.684] ? __pfx_filemap_add_folio+0x10/0x10 [464.691] ? __pfx___might_resched+0x10/0x10 [464.698] ? __filemap_get_folio+0x1c5/0x450 [464.705] prepare_uptodate_page+0x12e/0x4d0 [btrfs] [464.713] prepare_pages.constprop.0+0x13c/0x5c0 [btrfs] [464.721] ? fault_in_iov_iter_readable+0xd2/0x240 [464.729] btrfs_buffered_write+0x5bd/0x12f0 [btrfs] [464.737] ? __pfx_btrfs_buffered_write+0x10/0x10 [btrfs] [464.745] ? __pfx_lock_release+0x10/0x10 [464.752] ? generic_write_checks+0x275/0x400 [464.759] ? down_write+0x118/0x1f0 [464.765] ? up_write+0x19b/0x500 [464.770] btrfs_direct_write+0x731/0xba0 [btrfs] [464.778] ? __pfx_btrfs_direct_write+0x10/0x10 [btrfs] [464.785] ? __pfx___might_resched+0x10/0x10 [464.792] ? lock_acquire+0x435/0x500 [464.798] ? lock_acquire+0x435/0x500 [464.804] btrfs_do_write_iter+0x494/0x640 [btrfs] [464.811] ? __pfx_btrfs_do_write_iter+0x10/0x10 [btrfs] [464.819] ? __pfx___might_resched+0x10/0x10 [464.825] ? rw_verify_area+0x6d/0x590 [464.831] vfs_write+0x5d7/0xf50 [464.837] ? __might_fault+0x9d/0x120 [464.843] ? __pfx_vfs_write+0x10/0x10 [464.849] ? btrfs_file_llseek+0xb1/0xfb0 [btrfs] [464.856] ? lock_release+0x567/0x790 [464.862] ksys_write+0xfb/0x1d0 [464.867] ? __pfx_ksys_write+0x10/0x10 [464.873] ? _raw_spin_unlock+0x23/0x40 [464.879] ? btrfs_getattr+0x4af/0x670 [btrfs] [464.886] ? vfs_getattr_nosec+0x79/0x340 [464.892] do_syscall_64+0x95/0x180 [464.898] ? __do_sys_newfstat+0xde/0xf0 [464.904] ? __pfx___do_sys_newfstat+0x10/0x10 [464.911] ? trace_irq_enable.constprop.0+0xce/0x110 [464.918] ? syscall_exit_to_user_mode+0xac/0x2a0 [464.925] ? do_syscall_64+0xa1/0x180 [464.931] ? trace_irq_enable.constprop.0+0xce/0x110 [464.939] ? trace_irq_enable.constprop.0+0xce/0x110 [464.946] ? syscall_exit_to_user_mode+0xac/0x2a0 [464.953] ? btrfs_file_llseek+0xb1/0xfb0 [btrfs] [464.960] ? do_syscall_64+0xa1/0x180 [464.966] ? btrfs_file_llseek+0xb1/0xfb0 [btrfs] [464.973] ? trace_irq_enable.constprop.0+0xce/0x110 [464.980] ? syscall_exit_to_user_mode+0xac/0x2a0 [464.987] ? __pfx_btrfs_file_llseek+0x10/0x10 [btrfs] [464.995] ? trace_irq_enable.constprop.0+0xce/0x110 [465.002] ? __pfx_btrfs_file_llseek+0x10/0x10 [btrfs] [465.010] ? do_syscall_64+0xa1/0x180 [465.016] ? lock_release+0x567/0x790 [465.022] ? __pfx_lock_acquire+0x10/0x10 [465.028] ? __pfx_lock_release+0x10/0x10 [465.034] ? trace_irq_enable.constprop.0+0xce/0x110 [465.042] ? syscall_exit_to_user_mode+0xac/0x2a0 [465.049] ? do_syscall_64+0xa1/0x180 [465.055] ? syscall_exit_to_user_mode+0xac/0x2a0 [465.062] ? do_syscall_64+0xa1/0x180 [465.068] ? syscall_exit_to_user_mode+0xac/0x2a0 [465.075] ? do_syscall_64+0xa1/0x180 [465.081] ? clear_bhb_loop+0x25/0x80 [465.087] ? clear_bhb_loop+0x25/0x80 [465.093] ? clear_bhb_loop+0x25/0x80 [465.099] entry_SYSCALL_64_after_hwframe+0x76/0x7e [465.106] RIP: 0033:0x7f093b8ee784 [465.111] RSP: 002b:00007ffc29d31b28 EFLAGS: 00000202 ORIG_RAX: 0000000000000001 [465.122] RAX: ffffffffffffffda RBX: 0000000000006000 RCX: 00007f093b8ee784 [465.131] RDX: 000000000001de00 RSI: 00007f093b6ed200 RDI: 0000000000000003 [465.141] RBP: 000000000001de00 R08: 0000000000006000 R09: 0000000000000000 [465.150] R10: 0000000000023e00 R11: 0000000000000202 R12: 0000000000006000 [465.160] R13: 0000000000023e00 R14: 0000000000023e00 R15: 0000000000000001 [465.170] </TASK> [465.174] INFO: lockdep is turned off.
Reported-by: Shinichiro Kawasaki shinichiro.kawasaki@wdc.com Fixes: 97713b1a2ced ("btrfs: do not clear page dirty inside extent_write_locked_range()") Reviewed-by: Qu Wenruo wqu@suse.com Signed-off-by: Naohiro Aota naohiro.aota@wdc.com Signed-off-by: David Sterba dsterba@suse.com Conflicts: fs/btrfs/extent_io.c [conflicts due to not mergered 55151ea9ec1b ("btrfs: migrate subpage code to folio interfaces")] Signed-off-by: Long Li leo.lilong@huawei.com Signed-off-by: Yifan Qiao qiaoyifan4@huawei.com --- fs/btrfs/extent_io.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-)
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c index c6a95dfa59c8..b5a9248e7ee8 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -1355,6 +1355,13 @@ static noinline_for_stack int __extent_writepage_io(struct btrfs_inode *inode, free_extent_map(em); em = NULL;
+ /* + * Although the PageDirty bit might be cleared before entering + * this function, subpage dirty bit is not cleared. + * So clear subpage dirty bit here so next time we won't submit + * page for range already written to disk. + */ + btrfs_page_clear_dirty(fs_info, page, cur, iosize); btrfs_set_range_writeback(inode, cur, cur + iosize - 1); if (!PageWriteback(page)) { btrfs_err(inode->root->fs_info, @@ -1362,13 +1369,6 @@ static noinline_for_stack int __extent_writepage_io(struct btrfs_inode *inode, page->index, cur, end); }
- /* - * Although the PageDirty bit is cleared before entering this - * function, subpage dirty bit is not cleared. - * So clear subpage dirty bit here so next time we won't submit - * page for range already written to disk. - */ - btrfs_page_clear_dirty(fs_info, page, cur, iosize);
submit_extent_page(bio_ctrl, disk_bytenr, page, iosize, cur - page_offset(page));
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