# CVE-2023-53692: linux: In the Linux kernel, the following vulnerability has been resolved: ext4: fix use-after-free read in ext4_find_exten... CVE-2023-53692 is fixed in 20 products on 1 platform, first by ALAS2023-2023-184, released May 25, 2023. It is not reported as exploited. Patch Radar priority: High. - Web page: https://patchblox.com/security/cve/CVE-2023-53692 - Priority: High - CVSS: 7.8 (high) - EPSS: 0.0016 - CISA KEV: not listed - Exploited (vendor report): no - Publicly disclosed: no - Published: May 25, 2023 ## Description In the Linux kernel, the following vulnerability has been resolved: ext4: fix use-after-free read in ext4_find_extent for bigalloc + inline Syzbot found the following issue: loop0: detected capacity change from 0 to 2048 EXT4-fs (loop0): mounted filesystem 00000000-0000-0000-0000-000000000000 without journal. Quota mode: none. ================================================================== BUG: KASAN: use-after-free in ext4_ext_binsearch_idx fs/ext4/extents.c:768 [inline] BUG: KASAN: use-after-free in ext4_find_extent+0x76e/0xd90 fs/ext4/extents.c:931 Read of size 4 at addr ffff888073644750 by task syz-executor420/5067 CPU: 0 PID: 5067 Comm: syz-executor420 Not tainted 6.2.0-rc1-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x1b1/0x290 lib/dump_stack.c:106 print_address_description+0x74/0x340 mm/kasan/report.c:306 print_report+0x107/0x1f0 mm/kasan/report.c:417 kasan_report+0xcd/0x100 mm/kasan/report.c:517 ext4_ext_binsearch_idx fs/ext4/extents.c:768 [inline] ext4_find_extent+0x76e/0xd90 fs/ext4/extents.c:931 ext4_clu_mapped+0x117/0x970 fs/ext4/extents.c:5809 ext4_insert_delayed_block fs/ext4/inode.c:1696 [inline] ext4_da_map_blocks fs/ext4/inode.c:1806 [inline] ext4_da_get_block_prep+0x9e8/0x13c0 fs/ext4/inode.c:1870 ext4_block_write_begin+0x6a8/0x2290 fs/ext4/inode.c:1098 ext4_da_write_begin+0x539/0x760 fs/ext4/inode.c:3082 generic_perform_write+0x2e4/0x5e0 mm/filemap.c:3772 ext4_buffered_write_iter+0x122/0x3a0 fs/ext4/file.c:285 ext4_file_write_iter+0x1d0/0x18f0 call_write_iter include/linux/fs.h:2186 [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: 0033:0x7f4b7a9737b9 RSP: 002b:00007ffc5cac3668 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f4b7a9737b9 RDX: 00000000175d9003 RSI: 0000000020000200 RDI: 0000000000000004 RBP: 00007f4b7a933050 R08: 0000000000000000 R09: 0000000000000000 R10: 000000000000079f R11: 0000000000000246 R12: 00007f4b7a9330e0 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 Above issue is happens when enable bigalloc and inline data feature. As commit 131294c35ed6 fixed delayed allocation bug in ext4_clu_mapped for bigalloc + inline. But it only resolved issue when has inline data, if inline data has been converted to extent(ext4_da_convert_inline_data_to_extent) before writepages, there is no EXT4_STATE_MAY_INLINE_DATA flag. However i_data is still store inline data in this scene. Then will trigger UAF when find extent. To resolve above issue, there is need to add judge "ext4_has_inline_data(inode)" in ext4_clu_mapped(). ## Where it's fixed | Platform | Product | Fixed in | Fix | Released | |---|---|---|---|---| | Linux | bpftool amzn 2023 | 6.1.29-47.49.amzn2023 | [ALAS2023-2023-184](https://patchblox.com/security/data/fix/linux/alas2023-2023-184.md) | May 25, 2023 | | Linux | bpftool-debuginfo amzn 2023 | 6.1.29-47.49.amzn2023 | [ALAS2023-2023-184](https://patchblox.com/security/data/fix/linux/alas2023-2023-184.md) | May 25, 2023 | | Linux | kernel amzn 2023 | 6.1.29-47.49.amzn2023 | [ALAS2023-2023-184](https://patchblox.com/security/data/fix/linux/alas2023-2023-184.md) | May 25, 2023 | | Linux | kernel-debuginfo amzn 2023 | 6.1.29-47.49.amzn2023 | [ALAS2023-2023-184](https://patchblox.com/security/data/fix/linux/alas2023-2023-184.md) | May 25, 2023 | | Linux | kernel-debuginfo-common-aarch64 amzn 2023 | 6.1.29-47.49.amzn2023 | [ALAS2023-2023-184](https://patchblox.com/security/data/fix/linux/alas2023-2023-184.md) | May 25, 2023 | | Linux | kernel-debuginfo-common-x86_64 amzn 2023 | 6.1.29-47.49.amzn2023 | [ALAS2023-2023-184](https://patchblox.com/security/data/fix/linux/alas2023-2023-184.md) | May 25, 2023 | | Linux | kernel-devel amzn 2023 | 6.1.29-47.49.amzn2023 | [ALAS2023-2023-184](https://patchblox.com/security/data/fix/linux/alas2023-2023-184.md) | May 25, 2023 | | Linux | kernel-headers amzn 2023 | 6.1.29-47.49.amzn2023 | [ALAS2023-2023-184](https://patchblox.com/security/data/fix/linux/alas2023-2023-184.md) | May 25, 2023 | | Linux | kernel-libbpf amzn 2023 | 6.1.29-47.49.amzn2023 | [ALAS2023-2023-184](https://patchblox.com/security/data/fix/linux/alas2023-2023-184.md) | May 25, 2023 | | Linux | kernel-libbpf-devel amzn 2023 | 6.1.29-47.49.amzn2023 | [ALAS2023-2023-184](https://patchblox.com/security/data/fix/linux/alas2023-2023-184.md) | May 25, 2023 | | Linux | kernel-libbpf-static amzn 2023 | 6.1.29-47.49.amzn2023 | [ALAS2023-2023-184](https://patchblox.com/security/data/fix/linux/alas2023-2023-184.md) | May 25, 2023 | | Linux | kernel-livepatch-6.1.29-47.49 amzn 2023 | 1.0-0.amzn2023 | [ALAS2023-2023-184](https://patchblox.com/security/data/fix/linux/alas2023-2023-184.md) | May 25, 2023 | | Linux | kernel-tools amzn 2023 | 6.1.29-47.49.amzn2023 | [ALAS2023-2023-184](https://patchblox.com/security/data/fix/linux/alas2023-2023-184.md) | May 25, 2023 | | Linux | kernel-tools-debuginfo amzn 2023 | 6.1.29-47.49.amzn2023 | [ALAS2023-2023-184](https://patchblox.com/security/data/fix/linux/alas2023-2023-184.md) | May 25, 2023 | | Linux | kernel-tools-devel amzn 2023 | 6.1.29-47.49.amzn2023 | [ALAS2023-2023-184](https://patchblox.com/security/data/fix/linux/alas2023-2023-184.md) | May 25, 2023 | | Linux | linux Debian 12.15 (bookworm) | 6.1.37-1 | [DEBIAN-CVE-2023-53692](https://patchblox.com/security/data/fix/linux/debian-cve-2023-53692.md) | Oct 22, 2025 | | Linux | linux Debian 13.5 (trixie) | 6.3.7-1 | [DEBIAN-CVE-2023-53692](https://patchblox.com/security/data/fix/linux/debian-cve-2023-53692.md) | Oct 22, 2025 | | Linux | linux Debian 14 | 6.3.7-1 | [DEBIAN-CVE-2023-53692](https://patchblox.com/security/data/fix/linux/debian-cve-2023-53692.md) | Oct 22, 2025 | | Linux | perf amzn 2023 | 6.1.29-47.49.amzn2023 | [ALAS2023-2023-184](https://patchblox.com/security/data/fix/linux/alas2023-2023-184.md) | May 25, 2023 | | Linux | perf-debuginfo amzn 2023 | 6.1.29-47.49.amzn2023 | [ALAS2023-2023-184](https://patchblox.com/security/data/fix/linux/alas2023-2023-184.md) | May 25, 2023 | | Linux | python3-perf amzn 2023 | 6.1.29-47.49.amzn2023 | [ALAS2023-2023-184](https://patchblox.com/security/data/fix/linux/alas2023-2023-184.md) | May 25, 2023 | | Linux | python3-perf-debuginfo amzn 2023 | 6.1.29-47.49.amzn2023 | [ALAS2023-2023-184](https://patchblox.com/security/data/fix/linux/alas2023-2023-184.md) | May 25, 2023 | --- Data as of 2026-11-08T13:06:02Z UTC. 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