# CVE-2023-52737: linux: In the Linux kernel, the following vulnerability has been resolved:  btrfs: lock the inode in shared mode before star...

CVE-2023-52737 is fixed in 20 products on 1 platform, first by ALAS2023-2023-127, released March 11, 2023. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2023-52737
- Priority: Routine
- CVSS: 5.5 (medium)
- EPSS: 0.0021
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Mar 11, 2023

## Description

In the Linux kernel, the following vulnerability has been resolved:  btrfs: lock the inode in shared mode before starting fiemap  Currently fiemap does not take the inode's lock (VFS lock), it only locks a file range in the inode's io tree. This however can lead to a deadlock if we have a concurrent fsync on the file and fiemap code triggers a fault when accessing the user space buffer with fiemap_fill_next_extent(). The deadlock happens on the inode's i_mmap_lock semaphore, which is taken both by fsync and btrfs_page_mkwrite(). This deadlock was recently reported by syzbot and triggers a trace like the following:     task:syz-executor361 state:D stack:20264 pid:5668  ppid:5119   flags:0x00004004    Call Trace:     <TASK>     context_switch kernel/sched/core.c:5293 [inline]     __schedule+0x995/0xe20 kernel/sched/core.c:6606     schedule+0xcb/0x190 kernel/sched/core.c:6682     wait_on_state fs/btrfs/extent-io-tree.c:707 [inline]     wait_extent_bit+0x577/0x6f0 fs/btrfs/extent-io-tree.c:751     lock_extent+0x1c2/0x280 fs/btrfs/extent-io-tree.c:1742     find_lock_delalloc_range+0x4e6/0x9c0 fs/btrfs/extent_io.c:488     writepage_delalloc+0x1ef/0x540 fs/btrfs/extent_io.c:1863     __extent_writepage+0x736/0x14e0 fs/btrfs/extent_io.c:2174     extent_write_cache_pages+0x983/0x1220 fs/btrfs/extent_io.c:3091     extent_writepages+0x219/0x540 fs/btrfs/extent_io.c:3211     do_writepages+0x3c3/0x680 mm/page-writeback.c:2581     filemap_fdatawrite_wbc+0x11e/0x170 mm/filemap.c:388     __filemap_fdatawrite_range mm/filemap.c:421 [inline]     filemap_fdatawrite_range+0x175/0x200 mm/filemap.c:439     btrfs_fdatawrite_range fs/btrfs/file.c:3850 [inline]     start_ordered_ops fs/btrfs/file.c:1737 [inline]     btrfs_sync_file+0x4ff/0x1190 fs/btrfs/file.c:1839     generic_write_sync include/linux/fs.h:2885 [inline]     btrfs_do_write_iter+0xcd3/0x1280 fs/btrfs/file.c:1684     call_write_iter include/linux/fs.h:2189 [inline]     new_sync_write fs/read_write.c:491 [inline]     vfs_write+0x7dc/0xc50 fs/read_write.c:584     ksys_write+0x177/0x2a0 fs/read_write.c:637     do_syscall_x64 arch/x86/entry/common.c:50 [inline]     do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80     entry_SYSCALL_64_after_hwframe+0x63/0xcd    RIP: 0033:0x7f7d4054e9b9    RSP: 002b:00007f7d404fa2f8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001    RAX: ffffffffffffffda RBX: 00007f7d405d87a0 RCX: 00007f7d4054e9b9    RDX: 0000000000000090 RSI: 0000000020000000 RDI: 0000000000000006    RBP: 00007f7d405a51d0 R08: 0000000000000000 R09: 0000000000000000    R10: 0000000000000000 R11: 0000000000000246 R12: 61635f65646f6e69    R13: 65646f7475616f6e R14: 7261637369646f6e R15: 00007f7d405d87a8     </TASK>    INFO: task syz-executor361:5697 blocked for more than 145 seconds.          Not tainted 6.2.0-rc3-syzkaller-00376-g7c6984405241 #0    "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.    task:syz-executor361 state:D stack:21216 pid:5697  ppid:5119   flags:0x00004004    Call Trace:     <TASK>     context_switch kernel/sched/core.c:5293 [inline]     __schedule+0x995/0xe20 kernel/sched/core.c:6606     schedule+0xcb/0x190 kernel/sched/core.c:6682     rwsem_down_read_slowpath+0x5f9/0x930 kernel/locking/rwsem.c:1095     __down_read_common+0x54/0x2a0 kernel/locking/rwsem.c:1260     btrfs_page_mkwrite+0x417/0xc80 fs/btrfs/inode.c:8526     do_page_mkwrite+0x19e/0x5e0 mm/memory.c:2947     wp_page_shared+0x15e/0x380 mm/memory.c:3295     handle_pte_fault mm/memory.c:4949 [inline]     __handle_mm_fault mm/memory.c:5073 [inline]     handle_mm_fault+0x1b79/0x26b0 mm/memory.c:5219     do_user_addr_fault+0x69b/0xcb0 arch/x86/mm/fault.c:1428     handle_page_fault arch/x86/mm/fault.c:1519 [inline]     exc_page_fault+0x7a/0x110 arch/x86/mm/fault.c:1575     asm_exc_page_fault+0x22/0x30 arch/x86/include/asm/idtentry.h:570    RIP: 0010:copy_user_short_string+0xd/0x40 arch/x86/lib/copy_user_64.S:233    Code: 74 0a 89 (...)    RSP: 0018:ffffc9000570f330 EFLAGS: 000502 ---truncated---

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | bpftool amzn 2023 | 6.1.15-28.43.amzn2023 | [ALAS2023-2023-127](https://patchblox.com/security/data/fix/linux/alas2023-2023-127.md) | Mar 11, 2023 |
| Linux | bpftool-debuginfo amzn 2023 | 6.1.15-28.43.amzn2023 | [ALAS2023-2023-127](https://patchblox.com/security/data/fix/linux/alas2023-2023-127.md) | Mar 11, 2023 |
| Linux | kernel amzn 2023 | 6.1.15-28.43.amzn2023 | [ALAS2023-2023-127](https://patchblox.com/security/data/fix/linux/alas2023-2023-127.md) | Mar 11, 2023 |
| Linux | kernel-debuginfo amzn 2023 | 6.1.15-28.43.amzn2023 | [ALAS2023-2023-127](https://patchblox.com/security/data/fix/linux/alas2023-2023-127.md) | Mar 11, 2023 |
| Linux | kernel-debuginfo-common-aarch64 amzn 2023 | 6.1.15-28.43.amzn2023 | [ALAS2023-2023-127](https://patchblox.com/security/data/fix/linux/alas2023-2023-127.md) | Mar 11, 2023 |
| Linux | kernel-debuginfo-common-x86_64 amzn 2023 | 6.1.15-28.43.amzn2023 | [ALAS2023-2023-127](https://patchblox.com/security/data/fix/linux/alas2023-2023-127.md) | Mar 11, 2023 |
| Linux | kernel-devel amzn 2023 | 6.1.15-28.43.amzn2023 | [ALAS2023-2023-127](https://patchblox.com/security/data/fix/linux/alas2023-2023-127.md) | Mar 11, 2023 |
| Linux | kernel-headers amzn 2023 | 6.1.15-28.43.amzn2023 | [ALAS2023-2023-127](https://patchblox.com/security/data/fix/linux/alas2023-2023-127.md) | Mar 11, 2023 |
| Linux | kernel-libbpf amzn 2023 | 6.1.15-28.43.amzn2023 | [ALAS2023-2023-127](https://patchblox.com/security/data/fix/linux/alas2023-2023-127.md) | Mar 11, 2023 |
| Linux | kernel-libbpf-devel amzn 2023 | 6.1.15-28.43.amzn2023 | [ALAS2023-2023-127](https://patchblox.com/security/data/fix/linux/alas2023-2023-127.md) | Mar 11, 2023 |
| Linux | kernel-libbpf-static amzn 2023 | 6.1.15-28.43.amzn2023 | [ALAS2023-2023-127](https://patchblox.com/security/data/fix/linux/alas2023-2023-127.md) | Mar 11, 2023 |
| Linux | kernel-livepatch-6.1.15-28.43 amzn 2023 | 1.0-0.amzn2023 | [ALAS2023-2023-127](https://patchblox.com/security/data/fix/linux/alas2023-2023-127.md) | Mar 11, 2023 |
| Linux | kernel-tools amzn 2023 | 6.1.15-28.43.amzn2023 | [ALAS2023-2023-127](https://patchblox.com/security/data/fix/linux/alas2023-2023-127.md) | Mar 11, 2023 |
| Linux | kernel-tools-debuginfo amzn 2023 | 6.1.15-28.43.amzn2023 | [ALAS2023-2023-127](https://patchblox.com/security/data/fix/linux/alas2023-2023-127.md) | Mar 11, 2023 |
| Linux | kernel-tools-devel amzn 2023 | 6.1.15-28.43.amzn2023 | [ALAS2023-2023-127](https://patchblox.com/security/data/fix/linux/alas2023-2023-127.md) | Mar 11, 2023 |
| Linux | linux Debian 12.15 (bookworm) | 6.1.15-1 | [DEBIAN-CVE-2023-52737](https://patchblox.com/security/data/fix/linux/debian-cve-2023-52737.md) | May 21, 2024 |
| Linux | linux Debian 13.5 (trixie) | 6.1.15-1 | [DEBIAN-CVE-2023-52737](https://patchblox.com/security/data/fix/linux/debian-cve-2023-52737.md) | May 21, 2024 |
| Linux | linux Debian 14 | 6.1.15-1 | [DEBIAN-CVE-2023-52737](https://patchblox.com/security/data/fix/linux/debian-cve-2023-52737.md) | May 21, 2024 |
| Linux | perf amzn 2023 | 6.1.15-28.43.amzn2023 | [ALAS2023-2023-127](https://patchblox.com/security/data/fix/linux/alas2023-2023-127.md) | Mar 11, 2023 |
| Linux | perf-debuginfo amzn 2023 | 6.1.15-28.43.amzn2023 | [ALAS2023-2023-127](https://patchblox.com/security/data/fix/linux/alas2023-2023-127.md) | Mar 11, 2023 |
| Linux | python3-perf amzn 2023 | 6.1.15-28.43.amzn2023 | [ALAS2023-2023-127](https://patchblox.com/security/data/fix/linux/alas2023-2023-127.md) | Mar 11, 2023 |
| Linux | python3-perf-debuginfo amzn 2023 | 6.1.15-28.43.amzn2023 | [ALAS2023-2023-127](https://patchblox.com/security/data/fix/linux/alas2023-2023-127.md) | Mar 11, 2023 |

---

Data as of 2026-11-09T13:31:49Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

Free to use with attribution: show "Data: Patchblox Patch Radar" with a link to https://patchblox.com/security/patch-radar. Terms, including what needs a written agreement: https://patchblox.com/security/patch-radar/use-the-data

Product names, logos and trademarks shown on Patch Radar belong to their respective owners. They are used only to identify the software each security fix applies to and to help readers find their platform. Their use does not imply any affiliation with, or endorsement by, those owners, and Patchblox is not affiliated with any of them.