{"id":"CVE-2026-97416","state":"PUBLISHED","title":"btrfs: balance: fix potential bg lookup failure in btrfs_may_alloc_data_chunk()","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: balance: fix potential bg lookup failure in btrfs_may_alloc_data_chunk()\n\n[BUG]\nRunning btrfs balance can trigger a null-ptr-deref before relocating a\ndata chunk when metadata corruption leaves a chunk in the chunk tree\nwithout a corresponding block group in the in-memory cache:\n\n  KASAN: null-ptr-deref in range [0x0000000000000088-0x000000000000008f]\n  RIP: 0010:btrfs_may_alloc_data_chunk+0x40/0x1c0 fs/btrfs/volumes.c:3601\n  Call Trace:\n    __btrfs_balance fs/btrfs/volumes.c:4217 [inline]\n    btrfs_balance+0x2516/0x42b0 fs/btrfs/volumes.c:4604\n    btrfs_ioctl_balance fs/btrfs/ioctl.c:3577 [inline]\n    btrfs_ioctl+0x25cf/0x5b90 fs/btrfs/ioctl.c:5313\n    ...\n\n[CAUSE]\n__btrfs_balance() iterates the on-disk chunk tree and passes the chunk\nlogical bytenr to btrfs_may_alloc_data_chunk() before relocating a data\nchunk. That helper then queries the in-memory block group cache:\n\n  cache = btrfs_lookup_block_group(fs_info, chunk_offset);\n  chunk_type = cache->flags;   /* cache may be NULL */\n\nA corrupt image can contain a chunk item whose matching block group\nitem is missing, so no block group is ever inserted into the cache. In\nthat case btrfs_lookup_block_group() returns NULL.\n\nThe code only guards this with ASSERT(cache), which becomes a no-op when\nCONFIG_BTRFS_ASSERT is disabled. The subsequent dereference of\ncache->flags therefore crashes the kernel.\n\n[FIX]\nAdd a NULL check after btrfs_lookup_block_group() in\nbtrfs_may_alloc_data_chunk() and print and error message for clarity.","publishedAt":"2026-09-24T16:03:23.731Z","updatedAt":"2026-10-03T10:58:07.862Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"a6f93c71d412ba8ed743152c3a54ad0b78dcd9c7","status":"affected","lessThan":"9f37a6d6ae9e998232e2ba091ab4999cdf967e1b","versionType":"git"},{"version":"a6f93c71d412ba8ed743152c3a54ad0b78dcd9c7","status":"affected","lessThan":"e479236a8f4d85c4fb6b3f7c2556c21f583e2bf2","versionType":"git"},{"version":"a6f93c71d412ba8ed743152c3a54ad0b78dcd9c7","status":"affected","lessThan":"322f891b4d4fe64acb3351a0ffa62a7fa5ba7256","versionType":"git"},{"version":"a6f93c71d412ba8ed743152c3a54ad0b78dcd9c7","status":"affected","lessThan":"81a664ed8b1a44c76b204c4bd0d751317a02c5cd","versionType":"git"},{"version":"a6f93c71d412ba8ed743152c3a54ad0b78dcd9c7","status":"affected","lessThan":"9740dd0c17a4be8cc47a06c5ca5293471a7e286e","versionType":"git"},{"version":"a6f93c71d412ba8ed743152c3a54ad0b78dcd9c7","status":"affected","lessThan":"59f75e0c8724d4adebc08c7dd3ff2358b80c21f7","versionType":"git"},{"version":"a6f93c71d412ba8ed743152c3a54ad0b78dcd9c7","status":"affected","lessThan":"18d32b0013efba19f7ad3e5b08d7aee813d604a6","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/btrfs/volumes.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.16","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.16","versionType":"semver"},{"version":"5.10.271","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.222","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.189","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.158","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.111","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.53","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/btrfs/volumes.c"]}],"references":["https://git.kernel.org/stable/c/9f37a6d6ae9e998232e2ba091ab4999cdf967e1b","https://git.kernel.org/stable/c/e479236a8f4d85c4fb6b3f7c2556c21f583e2bf2","https://git.kernel.org/stable/c/322f891b4d4fe64acb3351a0ffa62a7fa5ba7256","https://git.kernel.org/stable/c/81a664ed8b1a44c76b204c4bd0d751317a02c5cd","https://git.kernel.org/stable/c/9740dd0c17a4be8cc47a06c5ca5293471a7e286e","https://git.kernel.org/stable/c/59f75e0c8724d4adebc08c7dd3ff2358b80c21f7","https://git.kernel.org/stable/c/18d32b0013efba19f7ad3e5b08d7aee813d604a6"],"weaknesses":[],"ingestedAt":"2026-10-29T20:13:43.249Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/97xxx/CVE-2026-97416.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-97416","state":"PUBLISHED","datePublished":"2026-09-24T16:03:23.731Z","dateUpdated":"2026-10-03T10:58:07.862Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-09-24T14:53:16.867Z"},"containers":{"cna":{"title":"btrfs: balance: fix potential bg lookup failure in btrfs_may_alloc_data_chunk()","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: balance: fix potential bg lookup failure in btrfs_may_alloc_data_chunk()\n\n[BUG]\nRunning btrfs balance can trigger a null-ptr-deref before relocating a\ndata chunk when metadata corruption leaves a chunk in the chunk tree\nwithout a corresponding block group in the in-memory cache:\n\n  KASAN: null-ptr-deref in range [0x0000000000000088-0x000000000000008f]\n  RIP: 0010:btrfs_may_alloc_data_chunk+0x40/0x1c0 fs/btrfs/volumes.c:3601\n  Call Trace:\n    __btrfs_balance fs/btrfs/volumes.c:4217 [inline]\n    btrfs_balance+0x2516/0x42b0 fs/btrfs/volumes.c:4604\n    btrfs_ioctl_balance fs/btrfs/ioctl.c:3577 [inline]\n    btrfs_ioctl+0x25cf/0x5b90 fs/btrfs/ioctl.c:5313\n    ...\n\n[CAUSE]\n__btrfs_balance() iterates the on-disk chunk tree and passes the chunk\nlogical bytenr to btrfs_may_alloc_data_chunk() before relocating a data\nchunk. That helper then queries the in-memory block group cache:\n\n  cache = btrfs_lookup_block_group(fs_info, chunk_offset);\n  chunk_type = cache->flags;   /* cache may be NULL */\n\nA corrupt image can contain a chunk item whose matching block group\nitem is missing, so no block group is ever inserted into the cache. In\nthat case btrfs_lookup_block_group() returns NULL.\n\nThe code only guards this with ASSERT(cache), which becomes a no-op when\nCONFIG_BTRFS_ASSERT is disabled. The subsequent dereference of\ncache->flags therefore crashes the kernel.\n\n[FIX]\nAdd a NULL check after btrfs_lookup_block_group() in\nbtrfs_may_alloc_data_chunk() and print and error message for clarity."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"a6f93c71d412ba8ed743152c3a54ad0b78dcd9c7","status":"affected","lessThan":"9f37a6d6ae9e998232e2ba091ab4999cdf967e1b","versionType":"git"},{"version":"a6f93c71d412ba8ed743152c3a54ad0b78dcd9c7","status":"affected","lessThan":"e479236a8f4d85c4fb6b3f7c2556c21f583e2bf2","versionType":"git"},{"version":"a6f93c71d412ba8ed743152c3a54ad0b78dcd9c7","status":"affected","lessThan":"322f891b4d4fe64acb3351a0ffa62a7fa5ba7256","versionType":"git"},{"version":"a6f93c71d412ba8ed743152c3a54ad0b78dcd9c7","status":"affected","lessThan":"81a664ed8b1a44c76b204c4bd0d751317a02c5cd","versionType":"git"},{"version":"a6f93c71d412ba8ed743152c3a54ad0b78dcd9c7","status":"affected","lessThan":"9740dd0c17a4be8cc47a06c5ca5293471a7e286e","versionType":"git"},{"version":"a6f93c71d412ba8ed743152c3a54ad0b78dcd9c7","status":"affected","lessThan":"59f75e0c8724d4adebc08c7dd3ff2358b80c21f7","versionType":"git"},{"version":"a6f93c71d412ba8ed743152c3a54ad0b78dcd9c7","status":"affected","lessThan":"18d32b0013efba19f7ad3e5b08d7aee813d604a6","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/btrfs/volumes.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.16","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.16","versionType":"semver"},{"version":"5.10.271","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.222","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.189","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.158","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.111","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.53","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/btrfs/volumes.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/9f37a6d6ae9e998232e2ba091ab4999cdf967e1b"},{"url":"https://git.kernel.org/stable/c/e479236a8f4d85c4fb6b3f7c2556c21f583e2bf2"},{"url":"https://git.kernel.org/stable/c/322f891b4d4fe64acb3351a0ffa62a7fa5ba7256"},{"url":"https://git.kernel.org/stable/c/81a664ed8b1a44c76b204c4bd0d751317a02c5cd"},{"url":"https://git.kernel.org/stable/c/9740dd0c17a4be8cc47a06c5ca5293471a7e286e"},{"url":"https://git.kernel.org/stable/c/59f75e0c8724d4adebc08c7dd3ff2358b80c21f7"},{"url":"https://git.kernel.org/stable/c/18d32b0013efba19f7ad3e5b08d7aee813d604a6"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-03T10:58:07.862Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.16","versionEndExcluding":"5.10.271"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.16","versionEndExcluding":"5.15.222"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.16","versionEndExcluding":"6.1.189"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.16","versionEndExcluding":"6.6.158"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.16","versionEndExcluding":"6.12.111"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.16","versionEndExcluding":"6.18.53"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.16","versionEndExcluding":"7.2"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}