In the Linux kernel, following vulnerability has been resolved: can: bcm: bcm_tx_setup(): fix KMSAN uninit-value in vfs_write Syzkaller reported issue: ===================================================== BUG: KMSAN: aio_rw_done fs/aio.c:1520 [inline] BUG: aio_write+0x899/0x950 fs/aio.c:1600 [inline] io_submit_one+0x1d1c/0x3bf0 fs/aio.c:2019 __do_sys_io_submit fs/aio.c:2078 __se_sys_io_submit+0x293/0x770 fs/aio.c:2048 __x64_sys_io_submit+0x92/0xd0 do_syscall_x64 arch/x86/entry/common.c:50 do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd Uninit was created at: slab_post_alloc_hook mm/slab.h:766 slab_alloc_node mm/slub.c:3452 __kmem_cache_alloc_node+0x71f/0xce0 mm/slub.c:3491 __do_kmalloc_node mm/slab_common.c:967 __kmalloc+0x11d/0x3b0 mm/slab_common.c:981 kmalloc_array include/linux/slab.h:636 bcm_tx_setup+0x80e/0x29d0 net/can/bcm.c:930 bcm_sendmsg+0x3a2/0xce0 net/can/bcm.c:1351 sock_sendmsg_nosec net/socket.c:714 sock_sendmsg net/socket.c:734 sock_write_iter+0x495/0x5e0 net/socket.c:1108 call_write_iter include/linux/fs.h:2189 aio_write+0x63a/0x950 entry_SYSCALL_64_after_hwframe+0x63/0xcd CPU: 1 PID: 5034 Comm: syz-executor350 Not tainted 6.2.0-rc6-syzkaller-80422-geda666ff2276 #0 Hardware name: Google Compute Engine/Google Engine, BIOS 01/12/2023 ===================================================== We can follow call chain and find that 'bcm_tx_setup' function calls 'memcpy_from_msg' to copy some content newly allocated frame of 'op->frames'. After 'len' field copied structure being compared with constant value (64 or 8). However, if 'memcpy_from_msg' returns an error, we will compare uninitialized memory. This triggers 'uninit-value' issue. This patch add possible errors processing to avoid issue. Tested via syzkaller