CVE-2024-35979

In the Linux kernel, the following vulnerability has been resolved: raid1:
fix use-after-free for original bio in raid1_write_request() r1_bio->bios[]
is used to record new bios that will be issued to underlying disks,
however, in raid1_write_request(), r1_bio->bios[] will set to the original
bio temporarily. Meanwhile, if blocked rdev is set, free_r1bio() will be
called causing that all r1_bio->bios[] to be freed: raid1_write_request()
r1_bio = alloc_r1bio(mddev, bio); -> r1_bio->bios[] is NULL for (i = 0; i <
disks; i++) -> for each rdev in conf // first rdev is normal
r1_bio->bios[0] = bio; -> set to original bio // second rdev is blocked if
(test_bit(Blocked, &rdev->flags)) break if (blocked_rdev) free_r1bio()
put_all_bios() bio_put(r1_bio->bios[0]) -> original bio is freed Test
scripts: mdadm -CR /dev/md0 -l1 -n4 /dev/sd[abcd] --assume-clean fio
-filename=/dev/md0 -ioengine=libaio -rw=write -bs=4k -numjobs=1
-iodepth=128 -name=test -direct=1 echo blocked >
/sys/block/md0/md/rd2/state Test result: BUG bio-264 (Not tainted): Object
already free

Allocated in mempool_alloc_slab+0x24/0x50 age=1 cpu=1 pid=869
kmem_cache_alloc+0x324/0x480 mempool_alloc_slab+0x24/0x50
mempool_alloc+0x6e/0x220 bio_alloc_bioset+0x1af/0x4d0
blkdev_direct_IO+0x164/0x8a0 blkdev_write_iter+0x309/0x440
aio_write+0x139/0x2f0 io_submit_one+0x5ca/0xb70
__do_sys_io_submit+0x86/0x270 __x64_sys_io_submit+0x22/0x30
do_syscall_64+0xb1/0x210 entry_SYSCALL_64_after_hwframe+0x6c/0x74 Freed in
mempool_free_slab+0x1f/0x30 age=1 cpu=1 pid=869 kmem_cache_free+0x28c/0x550
mempool_free_slab+0x1f/0x30 mempool_free+0x40/0x100 bio_free+0x59/0x80
bio_put+0xf0/0x220 free_r1bio+0x74/0xb0 raid1_make_request+0xadf/0x1150
md_handle_request+0xc7/0x3b0 md_submit_bio+0x76/0x130
__submit_bio+0xd8/0x1d0 submit_bio_noacct_nocheck+0x1eb/0x5c0
submit_bio_noacct+0x169/0xd40 submit_bio+0xee/0x1d0
blkdev_direct_IO+0x322/0x8a0 blkdev_write_iter+0x309/0x440
aio_write+0x139/0x2f0 Since that bios for underlying disks are not
allocated yet, fix this problem by using mempool_free() directly to free
the r1_bio.