{"id":"AZL-103586","summary":"CVE-2026-97416 affecting package kernel 6.6.157.1-1","details":"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-\u003eflags;   /* 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-\u003eflags 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.","modified":"2026-09-25T14:15:43.353945942Z","published":"2026-09-24T17:17:19Z","upstream":["CVE-2026-97416"],"references":[{"type":"WEB","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-97416"}],"affected":[{"package":{"name":"kernel","ecosystem":"Azure Linux:3","purl":"pkg:rpm/azure-linux/kernel"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"last_affected":"6.6.157.1-1"}]}],"database_specific":{"source":"https://github.com/microsoft/AzureLinuxVulnerabilityData/blob/main/osv/AZL-103586.json"}}],"schema_version":"1.9.0"}