From: Chao Yu yuchao0@huawei.com

mainline inclusion from mainline-v5.14-rc1 commit cad83c968c2ebe97905f900326988ed37146c347 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/I9RLZ0 CVE: CVE-2021-47335

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...

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As syzbot reported, there is an use-after-free issue during f2fs recovery:

Use-after-free write at 0xffff88823bc16040 (in kfence-#10): kmem_cache_destroy+0x1f/0x120 mm/slab_common.c:486 f2fs_recover_fsync_data+0x75b0/0x8380 fs/f2fs/recovery.c:869 f2fs_fill_super+0x9393/0xa420 fs/f2fs/super.c:3945 mount_bdev+0x26c/0x3a0 fs/super.c:1367 legacy_get_tree+0xea/0x180 fs/fs_context.c:592 vfs_get_tree+0x86/0x270 fs/super.c:1497 do_new_mount fs/namespace.c:2905 [inline] path_mount+0x196f/0x2be0 fs/namespace.c:3235 do_mount fs/namespace.c:3248 [inline] __do_sys_mount fs/namespace.c:3456 [inline] __se_sys_mount+0x2f9/0x3b0 fs/namespace.c:3433 do_syscall_64+0x3f/0xb0 arch/x86/entry/common.c:47 entry_SYSCALL_64_after_hwframe+0x44/0xae

The root cause is multi f2fs filesystem instances can race on accessing global fsync_entry_slab pointer, result in use-after-free issue of slab cache, fixes to init/destroy this slab cache only once during module init/destroy procedure to avoid this issue.

Reported-by: syzbot+9d90dad32dd9727ed084@syzkaller.appspotmail.com Signed-off-by: Chao Yu yuchao0@huawei.com Signed-off-by: Jaegeuk Kim jaegeuk@kernel.org

Conflicts: fs/f2fs/recovery.c fs/f2fs/super.c Signed-off-by: Ye Bin yebin10@huawei.com --- fs/f2fs/f2fs.h | 2 ++ fs/f2fs/recovery.c | 23 ++++++++++++++--------- fs/f2fs/super.c | 8 +++++++- 3 files changed, 23 insertions(+), 10 deletions(-)

diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h index 8cbc9da523dc..5627e02493c7 100644 --- a/fs/f2fs/f2fs.h +++ b/fs/f2fs/f2fs.h @@ -3095,6 +3095,8 @@ void f2fs_build_gc_manager(struct f2fs_sb_info *sbi); */ int f2fs_recover_fsync_data(struct f2fs_sb_info *sbi, bool check_only); bool f2fs_space_for_roll_forward(struct f2fs_sb_info *sbi); +int __init f2fs_create_recovery_cache(void); +void f2fs_destroy_recovery_cache(void);

/* * debug.c diff --git a/fs/f2fs/recovery.c b/fs/f2fs/recovery.c index 733f005b85d6..40afb6a213d8 100644 --- a/fs/f2fs/recovery.c +++ b/fs/f2fs/recovery.c @@ -683,13 +683,6 @@ int f2fs_recover_fsync_data(struct f2fs_sb_info *sbi, bool check_only) quota_enabled = f2fs_enable_quota_files(sbi, s_flags & SB_RDONLY); #endif

- fsync_entry_slab = f2fs_kmem_cache_create("f2fs_fsync_inode_entry", - sizeof(struct fsync_inode_entry)); - if (!fsync_entry_slab) { - err = -ENOMEM; - goto out; - } - INIT_LIST_HEAD(&inode_list); INIT_LIST_HEAD(&tmp_inode_list); INIT_LIST_HEAD(&dir_list); @@ -747,8 +740,6 @@ int f2fs_recover_fsync_data(struct f2fs_sb_info *sbi, bool check_only) } }

- kmem_cache_destroy(fsync_entry_slab); -out: #ifdef CONFIG_QUOTA /* Turn quotas off */ if (quota_enabled) @@ -758,3 +749,17 @@ int f2fs_recover_fsync_data(struct f2fs_sb_info *sbi, bool check_only)

return ret ? ret: err; } + +int __init f2fs_create_recovery_cache(void) +{ + fsync_entry_slab = f2fs_kmem_cache_create("f2fs_fsync_inode_entry", + sizeof(struct fsync_inode_entry)); + if (!fsync_entry_slab) + return -ENOMEM; + return 0; +} + +void f2fs_destroy_recovery_cache(void) +{ + kmem_cache_destroy(fsync_entry_slab); +} diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c index 7a9cc64f5ca3..cb2579e987aa 100644 --- a/fs/f2fs/super.c +++ b/fs/f2fs/super.c @@ -3305,9 +3305,12 @@ static int __init init_f2fs_fs(void) err = f2fs_create_checkpoint_caches(); if (err) goto free_segment_manager_caches; - err = f2fs_create_extent_cache(); + err = f2fs_create_recovery_cache(); if (err) goto free_checkpoint_caches; + err = f2fs_create_extent_cache(); + if (err) + goto free_recovery_cache; err = f2fs_init_sysfs(); if (err) goto free_extent_cache; @@ -3335,6 +3338,8 @@ static int __init init_f2fs_fs(void) f2fs_exit_sysfs(); free_extent_cache: f2fs_destroy_extent_cache(); +free_recovery_cache: + f2fs_destroy_recovery_cache(); free_checkpoint_caches: f2fs_destroy_checkpoint_caches(); free_segment_manager_caches: @@ -3355,6 +3360,7 @@ static void __exit exit_f2fs_fs(void) unregister_shrinker(&f2fs_shrinker_info); f2fs_exit_sysfs(); f2fs_destroy_extent_cache(); + f2fs_destroy_recovery_cache(); f2fs_destroy_checkpoint_caches(); f2fs_destroy_segment_manager_caches(); f2fs_destroy_node_manager_caches();