CVE-2026-74722

btrfs: fix memory leak in btrfs_do_encoded_write()

State: Published
Severity: Not scored
Published: Aug 22, 2026
Updated: Aug 22, 2026
Reserved: Aug 15, 2026

Description

In the Linux kernel, the following vulnerability has been resolved:

btrfs: fix memory leak in btrfs_do_encoded_write()

Local fuzzing of 6.12.94 has found the following memory leak:

Unreferenced object 0xffff888018050a80 (size 64): comm "syz.0.17", pid 10297, jiffies 4294953601 hex dump (first 32 bytes): 00 10 00 00 00 00 00 00 01 00 00 00 00 00 00 00 ................ 10 0a 05 18 80 88 ff ff 10 0a 05 18 80 88 ff ff ................ backtrace (crc a8a6fc29): kmemleak_alloc_recursive include/linux/kmemleak.h:42 [inline] slab_post_alloc_hook mm/slub.c:4152 [inline] slab_alloc_node mm/slub.c:4197 [inline] __kmalloc_cache_noprof+0x168/0x2c0 mm/slub.c:4358 kmalloc_noprof include/linux/slab.h:878 [inline] extent_changeset_alloc fs/btrfs/extent_io.h:207 [inline] qgroup_reserve_data+0x1c5/0x7d0 fs/btrfs/qgroup.c:4305 btrfs_qgroup_reserve_data+0x2e/0xb0 fs/btrfs/qgroup.c:4355 btrfs_do_encoded_write+0x92e/0x1040 fs/btrfs/inode.c:9746 btrfs_encoded_write fs/btrfs/file.c:1482 [inline] btrfs_do_write_iter+0x280/0x610 fs/btrfs/file.c:1507 btrfs_ioctl_encoded_write+0x3d6/0x490 fs/btrfs/ioctl.c:4738 btrfs_ioctl+0x6f9/0xc90 fs/btrfs/ioctl.c:-1 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:906 [inline] __se_sys_ioctl+0xf9/0x170 fs/ioctl.c:892 do_syscall_x64 arch/x86/entry/common.c:47 [inline] do_syscall_64+0xbe/0x1a0 arch/x86/entry/common.c:78 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Unreferenced object 0xffff888018050a00 (size 64): comm "syz.0.17", pid 10297, jiffies 4294953601 hex dump (first 32 bytes): 00 00 00 00 00 00 00 00 ff 0f 00 00 00 00 00 00 ................ 90 0a 05 18 80 88 ff ff 90 0a 05 18 80 88 ff ff ................ backtrace (crc cb5c9580): kmemleak_alloc_recursive include/linux/kmemleak.h:42 [inline] slab_post_alloc_hook mm/slub.c:4152 [inline] slab_alloc_node mm/slub.c:4197 [inline] __kmalloc_cache_noprof+0x168/0x2c0 mm/slub.c:4358 kmalloc_noprof include/linux/slab.h:878 [inline] kzalloc_noprof include/linux/slab.h:1014 [inline] ulist_prealloc+0x9c/0x110 fs/btrfs/ulist.c:114 extent_changeset_prealloc fs/btrfs/extent_io.h:217 [inline] __set_extent_bit+0x16b/0x1a70 fs/btrfs/extent-io-tree.c:1086 set_record_extent_bits+0x50/0x90 fs/btrfs/extent-io-tree.c:1821 qgroup_reserve_data+0x274/0x7d0 fs/btrfs/qgroup.c:4312 btrfs_qgroup_reserve_data+0x2e/0xb0 fs/btrfs/qgroup.c:4355 btrfs_do_encoded_write+0x92e/0x1040 fs/btrfs/inode.c:9746 btrfs_encoded_write fs/btrfs/file.c:1482 [inline] btrfs_do_write_iter+0x280/0x610 fs/btrfs/file.c:1507 btrfs_ioctl_encoded_write+0x3d6/0x490 fs/btrfs/ioctl.c:4738 btrfs_ioctl+0x6f9/0xc90 fs/btrfs/ioctl.c:-1 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:906 [inline] __se_sys_ioctl+0xf9/0x170 fs/ioctl.c:892 do_syscall_x64 arch/x86/entry/common.c:47 [inline] do_syscall_64+0xbe/0x1a0 arch/x86/entry/common.c:78 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Fix this by freeing an extent changeset before returning from btrfs_do_encoded_write().

Scores

The record has no CVSS score.

Weaknesses

The record names no weakness.

Affected Products

Product	Versions
LinuxLinux	7c0c7269f7b508ba6e4b063a9314d6bd1fb6db22 to before 0f0da96ccb1b9f35f4d3d4540dcaab0969d9d6b0Affected 7c0c7269f7b508ba6e4b063a9314d6bd1fb6db22 to before e2c7e88815edd5ecfb88e7660ab9fd42bda6bc47Affected 7c0c7269f7b508ba6e4b063a9314d6bd1fb6db22 to before 20c0eeb4313f9f89d47b80b672b5846f9827cb31Affected 7c0c7269f7b508ba6e4b063a9314d6bd1fb6db22 to before 24a8f2c29aebb753ccb962fbb25bae18d7978f6eAffected 7c0c7269f7b508ba6e4b063a9314d6bd1fb6db22 to before 60b50ceba6243802f8d2c0a9a7c2d549a93b1d64Affected 7c0c7269f7b508ba6e4b063a9314d6bd1fb6db22 to before d2a4e4e626b2f4670b69b430c357f03f53eb6632Affected
LinuxLinux	5.18Affected before 5.18Not affected 6.1.183 through 6.1.Not affected 6.6.152 through 6.6.Not affected 6.12.104 through 6.12.Not affected 6.18.45 through 6.18.Not affected 7.1.9 through 7.1.*Not affected 7.2 and laterNot affected

Product

Versions

LinuxLinux

7c0c7269f7b508ba6e4b063a9314d6bd1fb6db22 to before 0f0da96ccb1b9f35f4d3d4540dcaab0969d9d6b0Affected
7c0c7269f7b508ba6e4b063a9314d6bd1fb6db22 to before e2c7e88815edd5ecfb88e7660ab9fd42bda6bc47Affected
7c0c7269f7b508ba6e4b063a9314d6bd1fb6db22 to before 20c0eeb4313f9f89d47b80b672b5846f9827cb31Affected
7c0c7269f7b508ba6e4b063a9314d6bd1fb6db22 to before 24a8f2c29aebb753ccb962fbb25bae18d7978f6eAffected
7c0c7269f7b508ba6e4b063a9314d6bd1fb6db22 to before 60b50ceba6243802f8d2c0a9a7c2d549a93b1d64Affected
7c0c7269f7b508ba6e4b063a9314d6bd1fb6db22 to before d2a4e4e626b2f4670b69b430c357f03f53eb6632Affected

LinuxLinux

5.18Affected
before 5.18Not affected
6.1.183 through 6.1.*Not affected
6.6.152 through 6.6.*Not affected
6.12.104 through 6.12.*Not affected
6.18.45 through 6.18.*Not affected
7.1.9 through 7.1.*Not affected
7.2 and laterNot affected

References

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