Re: [syzbot] [fs?] UBSAN: shift-out-of-bounds in befs_check_sb

syzbot
2025-09-28T19:53:03Z

Hello,

syzbot tried to test the proposed patch but the build/boot failed:

./include/linux/thread_info.h:244:4: error: call to '__bad_copy_from' declared with 'error' attribute: copy source size is too small
drivers/nvme/target/fc.c:150:2: warning: 'counted_by' should not be applied to an array with element of unknown size because 'struct nvmet_fc_fcp_iod' is a struct type with a flexible array member. This will be an error in a future compiler version [-Wbounds-safety-counted-by-elt-type-unknown-size]

Tested on:

commit: 6f861765 fs: Block writes to mounted block devices
git tree: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel config: https://syzkaller.appspot.com/x/.config?x=f5b21423ca3f0a96
dashboard link: https://syzkaller.appspot.com/bug?extid=fc26c366038b54261e53
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8

Note: no patches were applied.