{"id":"AZL-53153","summary":"CVE-2024-50225 affecting package kernel 6.6.126.1-1","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: fix error propagation of split bios\n\nThe purpose of btrfs_bbio_propagate_error() shall be propagating an error\nof split bio to its original btrfs_bio, and tell the error to the upper\nlayer. However, it's not working well on some cases.\n\n* Case 1. Immediate (or quick) end_bio with an error\n\nWhen btrfs sends btrfs_bio to mirrored devices, btrfs calls\nbtrfs_bio_end_io() when all the mirroring bios are completed. If that\nbtrfs_bio was split, it is from btrfs_clone_bioset and its end_io function\nis btrfs_orig_write_end_io. For this case, btrfs_bbio_propagate_error()\naccesses the orig_bbio's bio context to increase the error count.\n\nThat works well in most cases. However, if the end_io is called enough\nfast, orig_bbio's (remaining part after split) bio context may not be\nproperly set at that time. Since the bio context is set when the orig_bbio\n(the last btrfs_bio) is sent to devices, that might be too late for earlier\nsplit btrfs_bio's completion.  That will result in NULL pointer\ndereference.\n\nThat bug is easily reproducible by running btrfs/146 on zoned devices [1]\nand it shows the following trace.\n\n[1] You need raid-stripe-tree feature as it create \"-d raid0 -m raid1\" FS.\n\n  BUG: kernel NULL pointer dereference, address: 0000000000000020\n  #PF: supervisor read access in kernel mode\n  #PF: error_code(0x0000) - not-present page\n  PGD 0 P4D 0\n  Oops: Oops: 0000 [#1] PREEMPT SMP PTI\n  CPU: 1 UID: 0 PID: 13 Comm: kworker/u32:1 Not tainted 6.11.0-rc7-BTRFS-ZNS+ #474\n  Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011\n  Workqueue: writeback wb_workfn (flush-btrfs-5)\n  RIP: 0010:btrfs_bio_end_io+0xae/0xc0 [btrfs]\n  BTRFS error (device dm-0): bdev /dev/mapper/error-test errs: wr 2, rd 0, flush 0, corrupt 0, gen 0\n  RSP: 0018:ffffc9000006f248 EFLAGS: 00010246\n  RAX: 0000000000000000 RBX: ffff888005a7f080 RCX: ffffc9000006f1dc\n  RDX: 0000000000000000 RSI: 000000000000000a RDI: ffff888005a7f080\n  RBP: ffff888011dfc540 R08: 0000000000000000 R09: 0000000000000001\n  R10: ffffffff82e508e0 R11: 0000000000000005 R12: ffff88800ddfbe58\n  R13: ffff888005a7f080 R14: ffff888005a7f158 R15: ffff888005a7f158\n  FS:  0000000000000000(0000) GS:ffff88803ea80000(0000) knlGS:0000000000000000\n  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033\n  CR2: 0000000000000020 CR3: 0000000002e22006 CR4: 0000000000370ef0\n  DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000\n  DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400\n  Call Trace:\n   \u003cTASK\u003e\n   ? __die_body.cold+0x19/0x26\n   ? page_fault_oops+0x13e/0x2b0\n   ? _printk+0x58/0x73\n   ? do_user_addr_fault+0x5f/0x750\n   ? exc_page_fault+0x76/0x240\n   ? asm_exc_page_fault+0x22/0x30\n   ? btrfs_bio_end_io+0xae/0xc0 [btrfs]\n   ? btrfs_log_dev_io_error+0x7f/0x90 [btrfs]\n   btrfs_orig_write_end_io+0x51/0x90 [btrfs]\n   dm_submit_bio+0x5c2/0xa50 [dm_mod]\n   ? find_held_lock+0x2b/0x80\n   ? blk_try_enter_queue+0x90/0x1e0\n   __submit_bio+0xe0/0x130\n   ? ktime_get+0x10a/0x160\n   ? lockdep_hardirqs_on+0x74/0x100\n   submit_bio_noacct_nocheck+0x199/0x410\n   btrfs_submit_bio+0x7d/0x150 [btrfs]\n   btrfs_submit_chunk+0x1a1/0x6d0 [btrfs]\n   ? lockdep_hardirqs_on+0x74/0x100\n   ? __folio_start_writeback+0x10/0x2c0\n   btrfs_submit_bbio+0x1c/0x40 [btrfs]\n   submit_one_bio+0x44/0x60 [btrfs]\n   submit_extent_folio+0x13f/0x330 [btrfs]\n   ? btrfs_set_range_writeback+0xa3/0xd0 [btrfs]\n   extent_writepage_io+0x18b/0x360 [btrfs]\n   extent_write_locked_range+0x17c/0x340 [btrfs]\n   ? __pfx_end_bbio_data_write+0x10/0x10 [btrfs]\n   run_delalloc_cow+0x71/0xd0 [btrfs]\n   btrfs_run_delalloc_range+0x176/0x500 [btrfs]\n   ? find_lock_delalloc_range+0x119/0x260 [btrfs]\n   writepage_delalloc+0x2ab/0x480 [btrfs]\n   extent_write_cache_pages+0x236/0x7d0 [btrfs]\n   btrfs_writepages+0x72/0x130 [btrfs]\n   do_writepages+0xd4/0x240\n   ? find_held_lock+0x2b/0x80\n   ? wbc_attach_and_unlock_inode+0x12c/0x290\n   ? wbc_attach_and_unlock_inode+0x12c/0x29\n---truncated---","modified":"2026-04-01T05:17:58.238699Z","published":"2024-11-09T11:15:07Z","upstream":["CVE-2024-50225"],"references":[{"type":"WEB","url":"https://nvd.nist.gov/vuln/detail/CVE-2024-50225"}],"affected":[{"package":{"name":"kernel","ecosystem":"Azure Linux:3","purl":"pkg:rpm/azure-linux/kernel"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"last_affected":"6.6.126.1-1"}]}],"database_specific":{"source":"https://github.com/microsoft/AzureLinuxVulnerabilityData/blob/main/osv/AZL-53153.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H"}]}