{"id":"CVE-2025-40119","state":"PUBLISHED","title":"ext4: fix potential null deref in ext4_mb_init()","description":"In the Linux kernel, the following vulnerability has been resolved:\n\next4: fix potential null deref in ext4_mb_init()\n\nIn ext4_mb_init(), ext4_mb_avg_fragment_size_destroy() may be called\nwhen sbi->s_mb_avg_fragment_size remains uninitialized (e.g., if groupinfo\nslab cache allocation fails). Since ext4_mb_avg_fragment_size_destroy()\nlacks null pointer checking, this leads to a null pointer dereference.\n\n==================================================================\nEXT4-fs: no memory for groupinfo slab cache\nBUG: kernel NULL pointer dereference, address: 0000000000000000\nPGD 0 P4D 0\nOops: Oops: 0002 [#1] SMP PTI\nCPU:2 UID: 0 PID: 87 Comm:mount Not tainted 6.17.0-rc2 #1134 PREEMPT(none)\nRIP: 0010:_raw_spin_lock_irqsave+0x1b/0x40\nCall Trace:\n <TASK>\n xa_destroy+0x61/0x130\n ext4_mb_init+0x483/0x540\n __ext4_fill_super+0x116d/0x17b0\n ext4_fill_super+0xd3/0x280\n get_tree_bdev_flags+0x132/0x1d0\n vfs_get_tree+0x29/0xd0\n do_new_mount+0x197/0x300\n __x64_sys_mount+0x116/0x150\n do_syscall_64+0x50/0x1c0\n entry_SYSCALL_64_after_hwframe+0x76/0x7e\n==================================================================\n\nTherefore, add necessary null check to ext4_mb_avg_fragment_size_destroy()\nto prevent this issue. The same fix is also applied to\next4_mb_largest_free_orders_destroy().","publishedAt":"2025-11-12T10:23:18.449Z","updatedAt":"2026-05-11T21:43:01.083Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"d99d714f714c9492dc64d8ab4329b083dbfa9cab","status":"affected","lessThan":"08d9175578d6a8e9b81921898fbf01aa669cd2be","versionType":"git"},{"version":"f7eaacbb4e54f8a6c6674c16eff54f703ea63d5e","status":"affected","lessThan":"00110f3cfc9b34b2dfee2a6c9e55a0ae6df125ae","versionType":"git"},{"version":"f7eaacbb4e54f8a6c6674c16eff54f703ea63d5e","status":"affected","lessThan":"3c3fac6bc0a9c00dbe65d8dc0d3a282afe4d3188","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/ext4/mballoc.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.17","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.17","versionType":"semver"},{"version":"6.17.3","status":"unaffected","lessThanOrEqual":"6.17.*","versionType":"semver"},{"version":"6.18","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/ext4/mballoc.c"]}],"references":["https://git.kernel.org/stable/c/08d9175578d6a8e9b81921898fbf01aa669cd2be","https://git.kernel.org/stable/c/00110f3cfc9b34b2dfee2a6c9e55a0ae6df125ae","https://git.kernel.org/stable/c/3c3fac6bc0a9c00dbe65d8dc0d3a282afe4d3188"],"weaknesses":[],"ingestedAt":"2026-10-29T20:09:09.358Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2025/40xxx/CVE-2025-40119.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2025-40119","state":"PUBLISHED","datePublished":"2025-11-12T10:23:18.449Z","dateUpdated":"2026-05-11T21:43:01.083Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2025-04-16T07:20:57.168Z"},"containers":{"cna":{"title":"ext4: fix potential null deref in ext4_mb_init()","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\next4: fix potential null deref in ext4_mb_init()\n\nIn ext4_mb_init(), ext4_mb_avg_fragment_size_destroy() may be called\nwhen sbi->s_mb_avg_fragment_size remains uninitialized (e.g., if groupinfo\nslab cache allocation fails). Since ext4_mb_avg_fragment_size_destroy()\nlacks null pointer checking, this leads to a null pointer dereference.\n\n==================================================================\nEXT4-fs: no memory for groupinfo slab cache\nBUG: kernel NULL pointer dereference, address: 0000000000000000\nPGD 0 P4D 0\nOops: Oops: 0002 [#1] SMP PTI\nCPU:2 UID: 0 PID: 87 Comm:mount Not tainted 6.17.0-rc2 #1134 PREEMPT(none)\nRIP: 0010:_raw_spin_lock_irqsave+0x1b/0x40\nCall Trace:\n <TASK>\n xa_destroy+0x61/0x130\n ext4_mb_init+0x483/0x540\n __ext4_fill_super+0x116d/0x17b0\n ext4_fill_super+0xd3/0x280\n get_tree_bdev_flags+0x132/0x1d0\n vfs_get_tree+0x29/0xd0\n do_new_mount+0x197/0x300\n __x64_sys_mount+0x116/0x150\n do_syscall_64+0x50/0x1c0\n entry_SYSCALL_64_after_hwframe+0x76/0x7e\n==================================================================\n\nTherefore, add necessary null check to ext4_mb_avg_fragment_size_destroy()\nto prevent this issue. The same fix is also applied to\next4_mb_largest_free_orders_destroy()."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"d99d714f714c9492dc64d8ab4329b083dbfa9cab","status":"affected","lessThan":"08d9175578d6a8e9b81921898fbf01aa669cd2be","versionType":"git"},{"version":"f7eaacbb4e54f8a6c6674c16eff54f703ea63d5e","status":"affected","lessThan":"00110f3cfc9b34b2dfee2a6c9e55a0ae6df125ae","versionType":"git"},{"version":"f7eaacbb4e54f8a6c6674c16eff54f703ea63d5e","status":"affected","lessThan":"3c3fac6bc0a9c00dbe65d8dc0d3a282afe4d3188","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/ext4/mballoc.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.17","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.17","versionType":"semver"},{"version":"6.17.3","status":"unaffected","lessThanOrEqual":"6.17.*","versionType":"semver"},{"version":"6.18","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/ext4/mballoc.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/08d9175578d6a8e9b81921898fbf01aa669cd2be"},{"url":"https://git.kernel.org/stable/c/00110f3cfc9b34b2dfee2a6c9e55a0ae6df125ae"},{"url":"https://git.kernel.org/stable/c/3c3fac6bc0a9c00dbe65d8dc0d3a282afe4d3188"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-05-11T21:43:01.083Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.17","versionEndExcluding":"6.17.3"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.17","versionEndExcluding":"6.18"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}