Vulnerability CVE-2024-26871
Published: 2024-04-17

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

f2fs: fix NULL pointer dereference in f2fs_submit_page_write()

BUG: kernel NULL pointer dereference, address: 0000000000000014
RIP: 0010:f2fs_submit_page_write+0x6cf/0x780 [f2fs]
Call Trace:
<TASK>
? show_regs+0x6e/0x80
? __die+0x29/0x70
? page_fault_oops+0x154/0x4a0
? prb_read_valid+0x20/0x30
? __irq_work_queue_local+0x39/0xd0
? irq_work_queue+0x36/0x70
? do_user_addr_fault+0x314/0x6c0
? exc_page_fault+0x7d/0x190
? asm_exc_page_fault+0x2b/0x30
? f2fs_submit_page_write+0x6cf/0x780 [f2fs]
? f2fs_submit_page_write+0x736/0x780 [f2fs]
do_write_page+0x50/0x170 [f2fs]
f2fs_outplace_write_data+0x61/0xb0 [f2fs]
f2fs_do_write_data_page+0x3f8/0x660 [f2fs]
f2fs_write_single_data_page+0x5bb/0x7a0 [f2fs]
f2fs_write_cache_pages+0x3da/0xbe0 [f2fs]
...
It is possible that other threads have added this fio to io->bio
and submitted the io->bio before entering f2fs_submit_page_write().
At this point io->bio = NULL.
If is_end_zone_blkaddr(sbi, fio->new_blkaddr) of this fio is true,
then an NULL pointer dereference error occurs at bio_get(io->bio).
The original code for determining zone end was after "out:",
which would have missed some fio who is zone end. I've moved
this code before "skip:" to make sure it's done for each fio.

 References:
https://git.kernel.org/stable/c/8e2ea8b04cb8d976110c4568509e67d6a39b2889
https://git.kernel.org/stable/c/4c122a32582b67bdd44ca8d25f894ee2dc54f566
https://git.kernel.org/stable/c/6d102382a11d5e6035f6c98f6e508a38541f7af3
https://git.kernel.org/stable/c/c2034ef6192a65a986a45c2aa2ed05824fdc0e9f
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