kernel/linux.git/fs/ext4/ioctl.c, branch v6.12.102

ext4: fix fd leak in EXT4_IOC_MOVE_EXT cross-sb validation

2026-07-25T06:02:24+00:00

The backport of upstream commit c143957520c6 ("ext4: validate donor file superblock early in EXT4_IOC_MOVE_EXT") uses a bare 'return -EXDEV' which is safe upstream because the fd is managed via CLASS(fd) with automatic cleanup (commit 8152f8201088 ("fdget(), more trivial conversions")). However, on 6.12.y the ioctl still uses the traditional fdget/fdput pattern, so the bare return bypasses fdput(donor) at the mext_out label, leaking the file reference. Fix by setting err and using goto mext_out. Fixes: 74796e886ca3 ("ext4: validate donor file superblock early in EXT4_IOC_MOVE_EXT") Reported-by: Harshit Mogalapalli Signed-off-by: Yun Zhou Signed-off-by: Greg Kroah-Hartman

ext4: validate donor file superblock early in EXT4_IOC_MOVE_EXT

2026-07-24T14:10:58+00:00

[ Upstream commit c143957520c6c9b5cd72e0de8b52b814f0c576fe ] Reject the EXT4_IOC_MOVE_EXT ioctl early if the donor file does not belong to the same superblock as the original file. Currently, this validation is performed inside ext4_move_extents() by mext_check_validity(), but only after lock_two_nondirectories() has already acquired the inode locks. When the donor fd refers to a file on a different filesystem (e.g., overlayfs), this late validation creates a circular lock dependency: CPU0 (overlayfs write) CPU1 (ext4 ioctl) ---- ---- inode_lock(ovl_inode) mnt_want_write_file(filp) sb_start_write(ext4_sb) [sb_writers] backing_file_write_iter() vfs_iter_write(real_file) file_start_write(real_file) sb_start_write(ext4_sb) [blocked by freeze] lock_two_nondirectories() inode_lock(ovl_inode) [blocked] With a concurrent freeze operation holding sb_writers write side, this forms a deadlock cycle: CPU0 waits for freeze to complete, freeze waits for CPU1's sb_writers reader to exit, CPU1 waits for CPU0's inode lock. Since EXT4_IOC_MOVE_EXT exchanges physical extents between two files, it fundamentally requires both files to reside on the same ext4 filesystem. Moving the superblock check before any lock acquisition is both semantically correct and eliminates the circular dependency by ensuring that cross-filesystem donor fds are rejected before sb_writers or inode locks are taken. Fixes: fcf6b1b729bc ("ext4: refactor ext4_move_extents code base") Reported-by: syzbot+ad6118a7584b607c67f2@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=ad6118a7584b607c67f2 Signed-off-by: Yun Zhou Reviewed-by: Jan Kara Reviewed-by: Andreas Dilger Link: https://patch.msgid.link/20260608152521.1292656-1-yun.zhou@windriver.com Signed-off-by: Theodore Ts'o Signed-off-by: Sasha Levin

ext4: fix LOGFLUSH shutdown ordering to allow ordered-mode data writeback

2026-07-24T14:10:52+00:00

[ Upstream commit d99748ef1695ce17eaf51c64b7a06952fa7cddab ] In EXT4_GOING_FLAGS_LOGFLUSH mode, the EXT4_FLAGS_SHUTDOWN flag was set before calling ext4_force_commit(). This caused ordered-mode data writeback (triggered by journal commit) to fail with -EIO, since ext4_do_writepages() checks for the shutdown flag. The journal would then be aborted prematurely before the commit could succeed. Fix this by calling ext4_force_commit() first, then setting the shutdown flag, so that pending data can be written back correctly. Note that moving ext4_force_commit() before setting the shutdown flag creates a small window in which new writes may occur and generate new journal transactions. When the journal is subsequently aborted, the new transactions will not be able to write to disk. This is intentional because LOGFLUSH's semantics are to flush pre-existing journal entries before shutdown, not to guarantee atomicity for writes that race with the ioctl. Fixes: 783d94854499 ("ext4: add EXT4_IOC_GOINGDOWN ioctl") Signed-off-by: Zhang Yi Reviewed-by: Baokun Li Reviewed-by: Jan Kara Link: https://patch.msgid.link/20260424104201.1930823-1-yi.zhang@huaweicloud.com Signed-off-by: Theodore Ts'o Signed-off-by: Sasha Levin

ext4: mark group extend fast-commit ineligible

2026-03-04T12:21:14+00:00

[ Upstream commit 1f8dd813a1c771b13c303f73d876164bc9b327cc ] Fast commits only log operations that have dedicated replay support. EXT4_IOC_GROUP_EXTEND grows the filesystem to the end of the last block group and updates the same on-disk metadata without going through the fast commit tracking paths. In practice these operations are rare and usually followed by further updates, but mixing them into a fast commit makes the overall semantics harder to reason about and risks replay gaps if new call sites appear. Teach ext4 to mark the filesystem fast-commit ineligible when EXT4_IOC_GROUP_EXTEND grows the filesystem. This forces those transactions to fall back to a full commit, ensuring that the group extension changes are captured by the normal journal rather than partially encoded in fast commit TLVs. This change should not affect common workloads but makes online resize via GROUP_EXTEND safer and easier to reason about under fast commit. Testing: 1. prepare: dd if=/dev/zero of=/root/fc_resize.img bs=1M count=0 seek=256 mkfs.ext4 -O fast_commit -F /root/fc_resize.img mkdir -p /mnt/fc_resize && mount -t ext4 -o loop /root/fc_resize.img /mnt/fc_resize 2. Extended the filesystem to the end of the last block group using a helper that calls EXT4_IOC_GROUP_EXTEND on the mounted filesystem and checked fc_info: ./group_extend_helper /mnt/fc_resize cat /proc/fs/ext4/loop0/fc_info shows the "Resize" ineligible reason increased. 3. Fsynced a file on the resized filesystem and confirmed that the fast commit ineligible counter incremented for the resize transaction: touch /mnt/fc_resize/file /root/fsync_file /mnt/fc_resize/file sync cat /proc/fs/ext4/loop0/fc_info Signed-off-by: Li Chen Link: https://patch.msgid.link/20251211115146.897420-6-me@linux.beauty Signed-off-by: Theodore Ts'o Signed-off-by: Sasha Levin

ext4: mark group add fast-commit ineligible

2026-03-04T12:21:14+00:00

[ Upstream commit 89b4336fd5ec78f51f9d3a1d100f3ffa3228e604 ] Fast commits only log operations that have dedicated replay support. Online resize via EXT4_IOC_GROUP_ADD updates the superblock and group descriptor metadata without going through the fast commit tracking paths. In practice these operations are rare and usually followed by further updates, but mixing them into a fast commit makes the overall semantics harder to reason about and risks replay gaps if new call sites appear. Teach ext4 to mark the filesystem fast-commit ineligible when ext4_ioctl_group_add() adds new block groups. This forces those transactions to fall back to a full commit, ensuring that the filesystem geometry updates are captured by the normal journal rather than partially encoded in fast commit TLVs. This change should not affect common workloads but makes online resize via GROUP_ADD safer and easier to reason about under fast commit. Testing: 1. prepare: dd if=/dev/zero of=/root/fc_resize.img bs=1M count=0 seek=256 mkfs.ext4 -O fast_commit -F /root/fc_resize.img mkdir -p /mnt/fc_resize && mount -t ext4 -o loop /root/fc_resize.img /mnt/fc_resize 2. Ran a helper that issues EXT4_IOC_GROUP_ADD on the mounted filesystem and checked the resize ineligible reason: ./group_add_helper /mnt/fc_resize cat /proc/fs/ext4/loop0/fc_info shows "Resize": > 0. 3. Fsynced a file on the resized filesystem and verified that the fast commit stats report at least one ineligible commit: touch /mnt/fc_resize/file /root/fsync_file /mnt/fc_resize/file sync cat /proc/fs/ext4/loop0/fc_info shows fc stats ineligible > 0. Signed-off-by: Li Chen Link: https://patch.msgid.link/20251211115146.897420-5-me@linux.beauty Signed-off-by: Theodore Ts'o Signed-off-by: Sasha Levin

introduce fd_file(), convert all accessors to it.

2024-08-13T02:00:43+00:00

For any changes of struct fd representation we need to turn existing accesses to fields into calls of wrappers. Accesses to struct fd::flags are very few (3 in linux/file.h, 1 in net/socket.c, 3 in fs/overlayfs/file.c and 3 more in explicit initializers). Those can be dealt with in the commit converting to new layout; accesses to struct fd::file are too many for that. This commit converts (almost) all of f.file to fd_file(f). It's not entirely mechanical ('file' is used as a member name more than just in struct fd) and it does not even attempt to distinguish the uses in pointer context from those in boolean context; the latter will be eventually turned into a separate helper (fd_empty()). NOTE: mass conversion to fd_empty(), tempting as it might be, is a bad idea; better do that piecewise in commit that convert from fdget...() to CLASS(...). [conflicts in fs/fhandle.c, kernel/bpf/syscall.c, mm/memcontrol.c caught by git; fs/stat.c one got caught by git grep] [fs/xattr.c conflict] Reviewed-by: Christian Brauner Signed-off-by: Al Viro

ext4: use memtostr_pad() for s_volume_name

2024-07-05T17:14:51+00:00

As with the other strings in struct ext4_super_block, s_volume_name is not NUL terminated. The other strings were marked in commit 072ebb3bffe6 ("ext4: add nonstring annotations to ext4.h"). Using strscpy() isn't the right replacement for strncpy(); it should use memtostr_pad() instead. Reported-by: syzbot+50835f73143cc2905b9e@syzkaller.appspotmail.com Closes: https://lore.kernel.org/all/00000000000019f4c00619192c05@google.com/ Fixes: 744a56389f73 ("ext4: replace deprecated strncpy with alternatives") Signed-off-by: Kees Cook Link: https://patch.msgid.link/20240523225408.work.904-kees@kernel.org Signed-off-by: Theodore Ts'o

ext4: replace deprecated strncpy with alternatives

2024-05-03T03:55:10+00:00

strncpy() is deprecated for use on NUL-terminated destination strings [1] and as such we should prefer more robust and less ambiguous string interfaces. in file.c: s_last_mounted is marked as __nonstring meaning it does not need to be NUL-terminated. Let's instead use strtomem_pad() to copy bytes from the string source to the byte array destination -- while also ensuring to pad with zeroes. in ioctl.c: We can drop the memset and size argument in favor of using the new 2-argument version of strscpy_pad() -- which was introduced with Commit e6584c3964f2f ("string: Allow 2-argument strscpy()"). This guarantees NUL-termination and NUL-padding on the destination buffer -- which seems to be a requirement judging from this comment: | static int ext4_ioctl_getlabel(struct ext4_sb_info *sbi, char __user *user_label) | { | char label[EXT4_LABEL_MAX + 1]; | | /* | * EXT4_LABEL_MAX must always be smaller than FSLABEL_MAX because | * FSLABEL_MAX must include terminating null byte, while s_volume_name | * does not have to. | */ in super.c: s_first_error_func is marked as __nonstring meaning we can take the same approach as in file.c; just use strtomem_pad() Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1] Link: https://manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html [2] Link: https://github.com/KSPP/linux/issues/90 Cc: linux-hardening@vger.kernel.org Signed-off-by: Justin Stitt Reviewed-by: Kees Cook Link: https://lore.kernel.org/r/20240321-strncpy-fs-ext4-file-c-v1-1-36a6a09fef0c@google.com Signed-off-by: Theodore Ts'o

ext4: remove unnecessary parameter "needed" in ext4_discard_preallocations

2024-01-18T15:52:45+00:00

The "needed" controls the number of ext4_prealloc_space to discard in ext4_discard_preallocations. Function ext4_discard_preallocations is supposed to discard all non-used preallocated blocks when "needed" is 0 and now ext4_discard_preallocations is always called with "needed" = 0. Remove unnecessary parameter "needed" and remove all non-used preallocated spaces in ext4_discard_preallocations to simplify the code. Note: If count of non-used preallocated spaces could be more than UINT_MAX, there was a memory leak as some non-used preallocated spaces are left ununsed and this commit will fix it. Otherwise, there is no behavior change. Signed-off-by: Kemeng Shi Reviewed-by: Jan Kara Link: https://lore.kernel.org/r/20240105092102.496631-9-shikemeng@huaweicloud.com Signed-off-by: Theodore Ts'o

bdev: rename freeze and thaw helpers

2023-11-18T13:59:23+00:00

We have bdev_mark_dead() etc and we're going to move block device freezing to holder ops in the next patch. Make the naming consistent: * freeze_bdev() -> bdev_freeze() * thaw_bdev() -> bdev_thaw() Also document the return code. Link: https://lore.kernel.org/r/20231024-vfs-super-freeze-v2-2-599c19f4faac@kernel.org Reviewed-by: Darrick J. Wong Reviewed-by: Christoph Hellwig Reviewed-by: Jan Kara Signed-off-by: Christian Brauner