CVE-2021-46958

In the Linux kernel, the following vulnerability has been resolved:

btrfs: fix race between transaction aborts and fsyncs leading to use-after-free

There is a race between a task aborting a transaction during a commit, a task doing an fsync and the transaction kthread, which leads to an use-after-free of the log root tree. When this happens, it results in a stack trace like the following:

BTRFS info (device dm-0): forced readonly BTRFS warning (device dm-0): Skipping commit of aborted transaction. BTRFS: error (device dm-0) in cleanup_transaction:1958: errno=-5 IO failure BTRFS warning (device dm-0): lost page write due to IO error on /dev/mapper/error-test (-5) BTRFS warning (device dm-0): Skipping commit of aborted transaction. BTRFS warning (device dm-0): direct IO failed ino 261 rw 0,0 sector 0xa4e8 len 4096 err no 10 BTRFS error (device dm-0): error writing primary super block to device 1 BTRFS warning (device dm-0): direct IO failed ino 261 rw 0,0 sector 0x12e000 len 4096 err no 10 BTRFS warning (device dm-0): direct IO failed ino 261 rw 0,0 sector 0x12e008 len 4096 err no 10 BTRFS warning (device dm-0): direct IO failed ino 261 rw 0,0 sector 0x12e010 len 4096 err no 10 BTRFS: error (device dm-0) in write_all_supers:4110: errno=-5 IO failure (1 errors while writing supers) BTRFS: error (device dm-0) in btrfs_sync_log:3308: errno=-5 IO failure general protection fault, probably for non-canonical address 0x6b6b6b6b6b6b6b68: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC PTI CPU: 2 PID: 2458471 Comm: fsstress Not tainted 5.12.0-rc5-btrfs-next-84 #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014 RIP: 0010:__mutex_lock+0x139/0xa40 Code: c0 74 19 (...) RSP: 0018:ffff9f18830d7b00 EFLAGS: 00010202 RAX: 6b6b6b6b6b6b6b68 RBX: 0000000000000001 RCX: 0000000000000002 RDX: ffffffffb9c54d13 RSI: 0000000000000000 RDI: 0000000000000000 RBP: ffff9f18830d7bc0 R08:...