The patch below does not apply to the 5.10-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.10.y git checkout FETCH_HEAD git cherry-pick -x 7c37c79510329cd951a4dedf3f7bf7e2b18dccec # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2025122900-cinnamon-repacking-8930@gregkh' --subject-prefix 'PATCH 5.10.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 7c37c79510329cd951a4dedf3f7bf7e2b18dccec Mon Sep 17 00:00:00 2001 From: Chao Yu chao@kernel.org Date: Mon, 20 Oct 2025 10:42:12 +0800 Subject: [PATCH] f2fs: fix to avoid updating zero-sized extent in extent cache

As syzbot reported:

F2FS-fs (loop0): __update_extent_tree_range: extent len is zero, type: 0, extent [0, 0, 0], age [0, 0] ------------[ cut here ]------------ kernel BUG at fs/f2fs/extent_cache.c:678! Oops: invalid opcode: 0000 [#1] SMP KASAN NOPTI CPU: 0 UID: 0 PID: 5336 Comm: syz.0.0 Not tainted syzkaller #0 PREEMPT(full) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014 RIP: 0010:__update_extent_tree_range+0x13bc/0x1500 fs/f2fs/extent_cache.c:678 Call Trace: <TASK> f2fs_update_read_extent_cache_range+0x192/0x3e0 fs/f2fs/extent_cache.c:1085 f2fs_do_zero_range fs/f2fs/file.c:1657 [inline] f2fs_zero_range+0x10c1/0x1580 fs/f2fs/file.c:1737 f2fs_fallocate+0x583/0x990 fs/f2fs/file.c:2030 vfs_fallocate+0x669/0x7e0 fs/open.c:342 ioctl_preallocate fs/ioctl.c:289 [inline] file_ioctl+0x611/0x780 fs/ioctl.c:-1 do_vfs_ioctl+0xb33/0x1430 fs/ioctl.c:576 __do_sys_ioctl fs/ioctl.c:595 [inline] __se_sys_ioctl+0x82/0x170 fs/ioctl.c:583 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f07bc58eec9

In error path of f2fs_zero_range(), it may add a zero-sized extent into extent cache, it should be avoided.

Fixes: 6e9619499f53 ("f2fs: support in batch fzero in dnode page") Cc: stable@kernel.org Reported-by: syzbot+24124df3170c3638b35f@syzkaller.appspotmail.com Closes: https://lore.kernel.org/linux-f2fs-devel/68e5d698.050a0220.256323.0032.GAE@g... Signed-off-by: Chao Yu chao@kernel.org Signed-off-by: Jaegeuk Kim jaegeuk@kernel.org

diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c index ffa045b39c01..c045e38e60ee 100644 --- a/fs/f2fs/file.c +++ b/fs/f2fs/file.c @@ -1654,8 +1654,11 @@ static int f2fs_do_zero_range(struct dnode_of_data *dn, pgoff_t start, f2fs_set_data_blkaddr(dn, NEW_ADDR); }

- f2fs_update_read_extent_cache_range(dn, start, 0, index - start); - f2fs_update_age_extent_cache_range(dn, start, index - start); + if (index > start) { + f2fs_update_read_extent_cache_range(dn, start, 0, + index - start); + f2fs_update_age_extent_cache_range(dn, start, index - start); + }

return ret; }