From: Ryusuke Konishi <konishi.ryusuke@gmail.com> stable inclusion from stable-v5.10.231 commit b017697a517f8779ada4e8ce1c2c75dbf60a2636 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IB5KQZ Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- commit cd45e963e44b0f10d90b9e6c0e8b4f47f3c92471 upstream. Patch series "nilfs2: fix null-ptr-deref bugs on block tracepoints". This series fixes null pointer dereference bugs that occur when using nilfs2 and two block-related tracepoints. This patch (of 2): It has been reported that when using "block:block_touch_buffer" tracepoint, touch_buffer() called from __nilfs_get_folio_block() causes a NULL pointer dereference, or a general protection fault when KASAN is enabled. This happens because since the tracepoint was added in touch_buffer(), it references the dev_t member bh->b_bdev->bd_dev regardless of whether the buffer head has a pointer to a block_device structure. In the current implementation, the block_device structure is set after the function returns to the caller. Here, touch_buffer() is used to mark the folio/page that owns the buffer head as accessed, but the common search helper for folio/page used by the caller function was optimized to mark the folio/page as accessed when it was reimplemented a long time ago, eliminating the need to call touch_buffer() here in the first place. So this solves the issue by eliminating the touch_buffer() call itself. Link: https://lkml.kernel.org/r/20241106160811.3316-1-konishi.ryusuke@gmail.com Link: https://lkml.kernel.org/r/20241106160811.3316-2-konishi.ryusuke@gmail.com Fixes: 5305cb830834 ("block: add block_{touch|dirty}_buffer tracepoint") Signed-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com> Reported-by: Ubisectech Sirius <bugreport@valiantsec.com> Closes: https://lkml.kernel.org/r/86bd3013-887e-4e38-960f-ca45c657f032.bugreport@val... Reported-by: syzbot+9982fb8d18eba905abe2@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=9982fb8d18eba905abe2 Tested-by: syzbot+9982fb8d18eba905abe2@syzkaller.appspotmail.com Cc: Tejun Heo <tj@kernel.org> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: He Yujie <coka.heyujie@huawei.com> --- fs/nilfs2/page.c | 1 - 1 file changed, 1 deletion(-) diff --git a/fs/nilfs2/page.c b/fs/nilfs2/page.c index 80f1f371d729..d2d6d5c761e8 100644 --- a/fs/nilfs2/page.c +++ b/fs/nilfs2/page.c @@ -39,7 +39,6 @@ __nilfs_get_page_block(struct page *page, unsigned long block, pgoff_t index, first_block = (unsigned long)index << (PAGE_SHIFT - blkbits); bh = nilfs_page_get_nth_block(page, block - first_block); - touch_buffer(bh); wait_on_buffer(bh); return bh; } -- 2.34.1