CVE-2026-43299
Full vulnerability record from the local CVENow database.
Description
In the Linux kernel, the following vulnerability has been resolved: btrfs: do not ASSERT() when the fs flips RO inside btrfs_repair_io_failure() [BUG] There is a bug report that when btrfs hits ENOSPC error in a critical path, btrfs flips RO (this part is expected, although the ENOSPC bug still needs to be addressed). The problem is after the RO flip, if there is a read repair pending, we can hit the ASSERT() inside btrfs_repair_io_failure() like the following: BTRFS info (device vdc): relocating block group 30408704 flags metadata|raid1 ------------[ cut here ]------------ BTRFS: Transaction aborted (error -28) WARNING: fs/btrfs/extent-tree.c:3235 at __btrfs_free_extent.isra.0+0x453/0xfd0, CPU#1: btrfs/383844 Modules linked in: kvm_intel kvm irqbypass [...] ---[ end trace 0000000000000000 ]--- BTRFS info (device vdc state EA): 2 enospc errors during balance BTRFS info (device vdc state EA): balance: ended with status: -30 BTRFS error (device vdc state EA): parent transid verify failed on logical 30556160 mirror 2 wanted 8 found 6 BTRFS error (device vdc state EA): bdev /dev/nvme0n1 errs: wr 0, rd 0, flush 0, corrupt 10, gen 0 [...] assertion failed: !(fs_info->sb->s_flags & SB_RDONLY) :: 0, in fs/btrfs/bio.c:938 ------------[ cut here ]------------ assertion failed: !(fs_info->sb->s_flags & SB_RDONLY) :: 0, in fs/btrfs/bio.c:938 kernel BUG at fs/btrfs/bio.c:938! Oops: invalid opcode: 0000 [#1] SMP NOPTI CPU: 0 UID: 0 PID: 868 Comm: kworker/u8:13 Tainted: G W N 6.19.0-rc6+ #4788 PREEMPT(full) Tainted: [W]=WARN, [N]=TEST Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.17.0-0-gb52ca86e094d-prebuilt.qemu.org 04/01/2014 Workqueue: btrfs-endio simple_end_io_work RIP: 0010:btrfs_repair_io_failure.cold+0xb2/0x120 RSP: 0000:ffffc90001d2bcf0 EFLAGS: 00010246 RAX: 0000000000000051 RBX: 0000000000001000 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffffffff8305cf42 RDI: 00000000ffffffff RBP: 0000000000000002 R08: 00000000fffeffff R09: ffffffff837fa988 R10: ffffffff8327a9e0 R11: 6f69747265737361 R12: ffff88813018d310 R13: ffff888168b8a000 R14: ffffc90001d2bd90 R15: ffff88810a169000 FS: 0000000000000000(0000) GS:ffff8885e752c000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 ------------[ cut here ]------------ [CAUSE] The cause of -ENOSPC error during the test case btrfs/124 is still unknown, although it's known that we still have cases where metadata can be over-committed but can not be fulfilled correctly, thus if we hit such ENOSPC error inside a critical path, we have no choice but abort the current transaction. This will mark the fs read-only. The problem is inside the btrfs_repair_io_failure() path that we require the fs not to be mount read-only. This is normally fine, but if we are doing a read-repair meanwhile the fs flips RO due to a critical error, we can enter btrfs_repair_io_failure() with super block set to read-only, thus triggering the above crash. [FIX] Just replace the ASSERT() with a proper return if the fs is already read-only.
View original CVE JSON
{
"id": "CVE-2026-43299",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"published": "2026-05-08T14:16:37.100",
"lastModified": "2026-10-30T13:18:50.050",
"vulnStatus": "Modified",
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: do not ASSERT() when the fs flips RO inside btrfs_repair_io_failure()\n\n[BUG]\nThere is a bug report that when btrfs hits ENOSPC error in a critical\npath, btrfs flips RO (this part is expected, although the ENOSPC bug\nstill needs to be addressed).\n\nThe problem is after the RO flip, if there is a read repair pending, we\ncan hit the ASSERT() inside btrfs_repair_io_failure() like the following:\n\n BTRFS info (device vdc): relocating block group 30408704 flags metadata|raid1\n ------------[ cut here ]------------\n BTRFS: Transaction aborted (error -28)\n WARNING: fs/btrfs/extent-tree.c:3235 at __btrfs_free_extent.isra.0+0x453/0xfd0, CPU#1: btrfs/383844\n Modules linked in: kvm_intel kvm irqbypass\n [...]\n ---[ end trace 0000000000000000 ]---\n BTRFS info (device vdc state EA): 2 enospc errors during balance\n BTRFS info (device vdc state EA): balance: ended with status: -30\n BTRFS error (device vdc state EA): parent transid verify failed on logical 30556160 mirror 2 wanted 8 found 6\n BTRFS error (device vdc state EA): bdev /dev/nvme0n1 errs: wr 0, rd 0, flush 0, corrupt 10, gen 0\n [...]\n assertion failed: !(fs_info->sb->s_flags & SB_RDONLY) :: 0, in fs/btrfs/bio.c:938\n ------------[ cut here ]------------\n assertion failed: !(fs_info->sb->s_flags & SB_RDONLY) :: 0, in fs/btrfs/bio.c:938\n kernel BUG at fs/btrfs/bio.c:938!\n Oops: invalid opcode: 0000 [#1] SMP NOPTI\n CPU: 0 UID: 0 PID: 868 Comm: kworker/u8:13 Tainted: G W N 6.19.0-rc6+ #4788 PREEMPT(full)\n Tainted: [W]=WARN, [N]=TEST\n Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.17.0-0-gb52ca86e094d-prebuilt.qemu.org 04/01/2014\n Workqueue: btrfs-endio simple_end_io_work\n RIP: 0010:btrfs_repair_io_failure.cold+0xb2/0x120\n RSP: 0000:ffffc90001d2bcf0 EFLAGS: 00010246\n RAX: 0000000000000051 RBX: 0000000000001000 RCX: 0000000000000000\n RDX: 0000000000000000 RSI: ffffffff8305cf42 RDI: 00000000ffffffff\n RBP: 0000000000000002 R08: 00000000fffeffff R09: ffffffff837fa988\n R10: ffffffff8327a9e0 R11: 6f69747265737361 R12: ffff88813018d310\n R13: ffff888168b8a000 R14: ffffc90001d2bd90 R15: ffff88810a169000\n FS: 0000000000000000(0000) GS:ffff8885e752c000(0000) knlGS:0000000000000000\n CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033\n ------------[ cut here ]------------\n\n[CAUSE]\nThe cause of -ENOSPC error during the test case btrfs/124 is still\nunknown, although it's known that we still have cases where metadata can\nbe over-committed but can not be fulfilled correctly, thus if we hit\nsuch ENOSPC error inside a critical path, we have no choice but abort\nthe current transaction.\n\nThis will mark the fs read-only.\n\nThe problem is inside the btrfs_repair_io_failure() path that we require\nthe fs not to be mount read-only. This is normally fine, but if we are\ndoing a read-repair meanwhile the fs flips RO due to a critical error,\nwe can enter btrfs_repair_io_failure() with super block set to\nread-only, thus triggering the above crash.\n\n[FIX]\nJust replace the ASSERT() with a proper return if the fs is already\nread-only."
}
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