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charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org On 9/14/23 15:08, Pavel Begunkov wrote: > On 9/14/23 15:06, Pavel Begunkov wrote: >> On 9/13/23 14:10, Pavel Begunkov wrote: >>> On 9/13/23 13:11, syzbot wrote: >>>> Hello, >>>> >>>> syzbot found the following issue on: >>>> >>>> HEAD commit:    0bb80ecc33a8 Linux 6.6-rc1 >>>> git tree:       upstream >>>> console+strace: https://syzkaller.appspot.com/x/log.txt?x=12d1eb78680000 >>>> kernel config:  https://syzkaller.appspot.com/x/.config?x=f4894cf58531f >>>> dashboard link: https://syzkaller.appspot.com/bug?extid=a4c6e5ef999b68b26ed1 >>>> compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40 >>>> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=16613002680000 >>>> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=13912e30680000 >>>> >>>> Downloadable assets: >>>> disk image: https://storage.googleapis.com/syzbot-assets/eeb0cac260c7/disk-0bb80ecc.raw.xz >>>> vmlinux: https://storage.googleapis.com/syzbot-assets/a3c360110254/vmlinux-0bb80ecc.xz >>>> kernel image: https://storage.googleapis.com/syzbot-assets/22b81065ba5f/bzImage-0bb80ecc.xz >>>> >>>> The issue was bisected to: >>>> >>>> commit 2af89abda7d9c2aeb573677e2c498ddb09f8058a >>>> Author: Pavel Begunkov >>>> Date:   Thu Aug 24 22:53:32 2023 +0000 >>>> >>>>      io_uring: add option to remove SQ indirection >>>> >>>> bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=15892e30680000 >>>> final oops:     https://syzkaller.appspot.com/x/report.txt?x=17892e30680000 >>>> console output: https://syzkaller.appspot.com/x/log.txt?x=13892e30680000 >>>> >>>> IMPORTANT: if you fix the issue, please add the following tag to the commit: >>>> Reported-by: syzbot+a4c6e5ef999b68b26ed1@syzkaller.appspotmail.com >>>> Fixes: 2af89abda7d9 ("io_uring: add option to remove SQ indirection") >>>> >>>> ================================================================================ >>>> UBSAN: array-index-out-of-bounds in io_uring/net.c:189:55 >>>> index 3779567444058 is out of range for type 'iovec [8]' >>>> CPU: 1 PID: 5039 Comm: syz-executor396 Not tainted 6.6.0-rc1-syzkaller #0 >>>> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/04/2023 >>>> Call Trace: >>>>   >>>>   __dump_stack lib/dump_stack.c:88 [inline] >>>>   dump_stack_lvl+0x125/0x1b0 lib/dump_stack.c:106 >>>>   ubsan_epilogue lib/ubsan.c:217 [inline] >>>>   __ubsan_handle_out_of_bounds+0x111/0x150 lib/ubsan.c:348 >>>>   io_setup_async_msg+0x2a0/0x2b0 io_uring/net.c:189 >>> >>> Which is >>> >>> /* if were using fast_iov, set it to the new one */ >>> if (iter_is_iovec(&kmsg->msg.msg_iter) && !kmsg->free_iov) { >>>      size_t fast_idx = iter_iov(&kmsg->msg.msg_iter) - kmsg->fast_iov; >>>      async_msg->msg.msg_iter.__iov = &async_msg->fast_iov[fast_idx]; >>> } >>> >>> The bisection doesn't immediately make sense, I'll try >>> it out >> >> #syz test: https://github.com/isilence/linux.git netmsg-init-base >> >> First just test upstream because I'm curious about reproducibility > > Couldn't repro myself, I think this is the fix #syz test: https://github.com/isilence/linux.git syz-test/netmsg-init -- Pavel Begunkov