In the Linux kernel, the following vulnerability has been resolved:
fs: jfs: Fix UBSAN: array-index-out-of-bounds in dbAllocDmapLev
Syzkaller reported the following issue:
UBSAN: array-index-out-of-bounds in fs/jfs/jfs_dmap.c:1965:6 index -84 is out of range for type 's8[341]' (aka 'signed char[341]') CPU: 1 PID: 4995 Comm: syz-executor146 Not tainted 6.4.0-rc6-syzkaller-00037-gb6dad5178cea #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/27/2023 Call Trace: <TASK> __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x1e7/0x2d0 lib/dump_stack.c:106 ubsan_epilogue lib/ubsan.c:217 [inline] __ubsan_handle_out_of_bounds+0x11c/0x150 lib/ubsan.c:348 dbAllocDmapLev+0x3e5/0x430 fs/jfs/jfs_dmap.c:1965 dbAllocCtl+0x113/0x920 fs/jfs/jfs_dmap.c:1809 dbAllocAG+0x28f/0x10b0 fs/jfs/jfs_dmap.c:1350 dbAlloc+0x658/0xca0 fs/jfs/jfs_dmap.c:874 dtSplitUp fs/jfs/jfs_dtree.c:974 [inline] dtInsert+0xda7/0x6b00 fs/jfs/jfs_dtree.c:863 jfs_create+0x7b6/0xbb0 fs/jfs/namei.c:137 lookup_open fs/namei.c:3492 [inline] open_last_lookups fs/namei.c:3560 [inline] path_openat+0x13df/0x3170 fs/namei.c:3788 do_filp_open+0x234/0x490 fs/namei.c:3818 do_sys_openat2+0x13f/0x500 fs/open.c:1356 do_sys_open fs/open.c:1372 [inline] __do_sys_openat fs/open.c:1388 [inline] __se_sys_openat fs/open.c:1383 [inline] __x64_sys_openat+0x247/0x290 fs/open.c:1383 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd RIP: 0033:0x7f1f4e33f7e9 Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 51 14 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ffc21129578 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f1f4e33f7e9 RDX: 000000000000275a RSI: 0000000020000040 RDI: 00000000ffffff9c RBP: 00007f1f4e2ff080 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f1f4e2ff110 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 </TASK>
The bug occurs when the dbAllocDmapLev()function attempts to access dp->tree.stree[leafidx + LEAFIND] while the leafidx value is negative.
To rectify this, the patch introduces a safeguard within the dbAllocDmapLev() function. A check has been added to verify if leafidx is negative. If it is, the function immediately returns an I/O error, preventing any further execution that could potentially cause harm.
Tested via syzbot.
CVSS Details
- CVSS 3.1 Base Score: 7.8
- CVSS 3.1 Vector: (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H)
Covered by Rapid7
| Product | Vendor Advisory | Solution File | Added | Published |
|---|---|---|---|---|
| Amazon Linux Ami 2 | — | Upgrade python-perfUpgrade bpftoolUpgrade kernel-debuginfo-common-x86_64Upgrade kernel-tools-debuginfoUpgrade bpftool-debuginfoUpgrade kernel-livepatch-4.14.326-245.539Upgrade kernel-headersUpgrade kernel-toolsUpgrade kernel-debuginfoUpgrade kernel-livepatch-5.10.192-182.736Upgrade kernel-tools-develUpgrade kernel-debuginfo-common-aarch64Upgrade perf-debuginfoUpgrade kernelUpgrade kernel-develUpgrade perfUpgrade python-perf-debuginfo | May 20, 2026 | May 20, 2026 |
| Debian | — | Upgrade linux | Oct 3, 2025 | Oct 3, 2025 |
| Redhat_linux | — | No solution exists | Jul 17, 2026 | Oct 1, 2025 |
| Ubuntu | — | Upgrade linux-hwe-5.4Upgrade linux-azure-5.4Upgrade linux-xilinx-zynqmpUpgrade linux-intel-iot-realtimeUpgrade linux-nvidia-tegra-igxUpgrade linux-ibmUpgrade linux-oracleUpgrade linux-riscv-5.15Upgrade linux-nvidiaUpgrade linux-azure-5.15Upgrade linux-azure-fipsUpgrade linux-intel-iotgUpgrade linux-kvmUpgrade linux-intel-iotg-5.15Upgrade linux-gcp-5.4Upgrade linux-ibm-5.4Upgrade linuxUpgrade linux-aws-fipsUpgrade linux-oracle-5.15Upgrade linux-lowlatencyUpgrade linux-gcp-fipsUpgrade linux-gkeopUpgrade linux-fipsUpgrade linux-gkeUpgrade linux-realtimeUpgrade linux-ibm-5.15Upgrade linux-gcp-5.15Upgrade linux-raspiUpgrade linux-oracle-5.4Upgrade linux-azureUpgrade linux-raspi-5.4Upgrade linux-iotUpgrade linux-gcpUpgrade linux-hwe-5.15Upgrade linux-bluefieldUpgrade linux-aws-5.4Upgrade linux-aws-5.15Upgrade linux-awsUpgrade linux-nvidia-tegraUpgrade linux-nvidia-tegra-5.15Upgrade linux-lowlatency-hwe-5.15 | Oct 10, 2025 | Oct 1, 2025 |
| Vmware Photon_os | — | Use 'tdnf update' to upgrade all packages to the latest version. | Oct 15, 2025 | Oct 1, 2025 |
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