* [syzbot] linux-next boot error: BUG: unable to handle kernel paging request in kernel_execve @ 2022-08-11 7:29 syzbot 2022-08-11 15:33 ` Kees Cook 0 siblings, 1 reply; 8+ messages in thread From: syzbot @ 2022-08-11 7:29 UTC (permalink / raw) To: ebiederm, keescook, linux-fsdevel, linux-kernel, linux-mm, linux-next, sfr, syzkaller-bugs, viro Hello, syzbot found the following issue on: HEAD commit: bc6c6584ffb2 Add linux-next specific files for 20220810 git tree: linux-next console output: https://syzkaller.appspot.com/x/log.txt?x=115034c3080000 kernel config: https://syzkaller.appspot.com/x/.config?x=5784be4315a4403b dashboard link: https://syzkaller.appspot.com/bug?extid=3250d9c8925ef29e975f compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2 IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+3250d9c8925ef29e975f@syzkaller.appspotmail.com BUG: unable to handle page fault for address: ffffdc0000000000 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 11826067 P4D 11826067 PUD 0 Oops: 0000 [#1] PREEMPT SMP KASAN CPU: 0 PID: 1100 Comm: kworker/u4:5 Not tainted 5.19.0-next-20220810-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/22/2022 RIP: 0010:strnlen+0x3b/0x70 lib/string.c:504 Code: 74 3c 48 bb 00 00 00 00 00 fc ff df 49 89 fc 48 89 f8 eb 09 48 83 c0 01 48 39 e8 74 1e 48 89 c2 48 89 c1 48 c1 ea 03 83 e1 07 <0f> b6 14 1a 38 ca 7f 04 84 d2 75 11 80 38 00 75 d9 4c 29 e0 48 83 RSP: 0000:ffffc90005c5fe10 EFLAGS: 00010246 RAX: ffff000000000000 RBX: dffffc0000000000 RCX: 0000000000000000 RDX: 1fffe00000000000 RSI: 0000000000020000 RDI: ffff000000000000 RBP: ffff000000020000 R08: 0000000000000005 R09: 0000000000000000 R10: 0000000000000006 R11: 0000000000000000 R12: ffff000000000000 R13: ffff88814764cc00 R14: ffff000000000000 R15: ffff88814764cc00 FS: 0000000000000000(0000) GS:ffff8880b9a00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffdc0000000000 CR3: 000000000bc8e000 CR4: 00000000003506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <TASK> strnlen include/linux/fortify-string.h:119 [inline] copy_string_kernel+0x26/0x250 fs/exec.c:616 copy_strings_kernel+0xb3/0x190 fs/exec.c:655 kernel_execve+0x377/0x500 fs/exec.c:1998 call_usermodehelper_exec_async+0x2e3/0x580 kernel/umh.c:112 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306 </TASK> Modules linked in: CR2: ffffdc0000000000 ---[ end trace 0000000000000000 ]--- RIP: 0010:strnlen+0x3b/0x70 lib/string.c:504 Code: 74 3c 48 bb 00 00 00 00 00 fc ff df 49 89 fc 48 89 f8 eb 09 48 83 c0 01 48 39 e8 74 1e 48 89 c2 48 89 c1 48 c1 ea 03 83 e1 07 <0f> b6 14 1a 38 ca 7f 04 84 d2 75 11 80 38 00 75 d9 4c 29 e0 48 83 RSP: 0000:ffffc90005c5fe10 EFLAGS: 00010246 RAX: ffff000000000000 RBX: dffffc0000000000 RCX: 0000000000000000 RDX: 1fffe00000000000 RSI: 0000000000020000 RDI: ffff000000000000 RBP: ffff000000020000 R08: 0000000000000005 R09: 0000000000000000 R10: 0000000000000006 R11: 0000000000000000 R12: ffff000000000000 R13: ffff88814764cc00 R14: ffff000000000000 R15: ffff88814764cc00 FS: 0000000000000000(0000) GS:ffff8880b9a00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffdc0000000000 CR3: 000000000bc8e000 CR4: 00000000003506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 ---------------- Code disassembly (best guess): 0: 74 3c je 0x3e 2: 48 bb 00 00 00 00 00 movabs $0xdffffc0000000000,%rbx 9: fc ff df c: 49 89 fc mov %rdi,%r12 f: 48 89 f8 mov %rdi,%rax 12: eb 09 jmp 0x1d 14: 48 83 c0 01 add $0x1,%rax 18: 48 39 e8 cmp %rbp,%rax 1b: 74 1e je 0x3b 1d: 48 89 c2 mov %rax,%rdx 20: 48 89 c1 mov %rax,%rcx 23: 48 c1 ea 03 shr $0x3,%rdx 27: 83 e1 07 and $0x7,%ecx * 2a: 0f b6 14 1a movzbl (%rdx,%rbx,1),%edx <-- trapping instruction 2e: 38 ca cmp %cl,%dl 30: 7f 04 jg 0x36 32: 84 d2 test %dl,%dl 34: 75 11 jne 0x47 36: 80 38 00 cmpb $0x0,(%rax) 39: 75 d9 jne 0x14 3b: 4c 29 e0 sub %r12,%rax 3e: 48 rex.W 3f: 83 .byte 0x83 --- This report is generated by a bot. It may contain errors. See https://goo.gl/tpsmEJ for more information about syzbot. syzbot engineers can be reached at syzkaller@googlegroups.com. syzbot will keep track of this issue. See: https://goo.gl/tpsmEJ#status for how to communicate with syzbot. ^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [syzbot] linux-next boot error: BUG: unable to handle kernel paging request in kernel_execve 2022-08-11 7:29 [syzbot] linux-next boot error: BUG: unable to handle kernel paging request in kernel_execve syzbot @ 2022-08-11 15:33 ` Kees Cook 2022-08-11 17:39 ` Ira Weiny 0 siblings, 1 reply; 8+ messages in thread From: Kees Cook @ 2022-08-11 15:33 UTC (permalink / raw) To: Fabio M. De Francesco Cc: ebiederm, linux-fsdevel, linux-kernel, linux-mm, linux-next, sfr, syzkaller-bugs, viro, syzbot, Ira Weiny Hi Fabio, It seems likely that the kmap change[1] might be causing this crash. Is there a boot-time setup race between kmap being available and early umh usage? -Kees [1] https://git.kernel.org/linus/c6e8e36c6ae4b11bed5643317afb66b6c3cadba8 On Thu, Aug 11, 2022 at 12:29:34AM -0700, syzbot wrote: > Hello, > > syzbot found the following issue on: > > HEAD commit: bc6c6584ffb2 Add linux-next specific files for 20220810 > git tree: linux-next > console output: https://syzkaller.appspot.com/x/log.txt?x=115034c3080000 > kernel config: https://syzkaller.appspot.com/x/.config?x=5784be4315a4403b > dashboard link: https://syzkaller.appspot.com/bug?extid=3250d9c8925ef29e975f > compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2 > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+3250d9c8925ef29e975f@syzkaller.appspotmail.com > > BUG: unable to handle page fault for address: ffffdc0000000000 > #PF: supervisor read access in kernel mode > #PF: error_code(0x0000) - not-present page > PGD 11826067 P4D 11826067 PUD 0 > Oops: 0000 [#1] PREEMPT SMP KASAN > CPU: 0 PID: 1100 Comm: kworker/u4:5 Not tainted 5.19.0-next-20220810-syzkaller #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/22/2022 > RIP: 0010:strnlen+0x3b/0x70 lib/string.c:504 > Code: 74 3c 48 bb 00 00 00 00 00 fc ff df 49 89 fc 48 89 f8 eb 09 48 83 c0 01 48 39 e8 74 1e 48 89 c2 48 89 c1 48 c1 ea 03 83 e1 07 <0f> b6 14 1a 38 ca 7f 04 84 d2 75 11 80 38 00 75 d9 4c 29 e0 48 83 > RSP: 0000:ffffc90005c5fe10 EFLAGS: 00010246 > RAX: ffff000000000000 RBX: dffffc0000000000 RCX: 0000000000000000 > RDX: 1fffe00000000000 RSI: 0000000000020000 RDI: ffff000000000000 > RBP: ffff000000020000 R08: 0000000000000005 R09: 0000000000000000 > R10: 0000000000000006 R11: 0000000000000000 R12: ffff000000000000 > R13: ffff88814764cc00 R14: ffff000000000000 R15: ffff88814764cc00 > FS: 0000000000000000(0000) GS:ffff8880b9a00000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: ffffdc0000000000 CR3: 000000000bc8e000 CR4: 00000000003506f0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > Call Trace: > <TASK> > strnlen include/linux/fortify-string.h:119 [inline] > copy_string_kernel+0x26/0x250 fs/exec.c:616 > copy_strings_kernel+0xb3/0x190 fs/exec.c:655 > kernel_execve+0x377/0x500 fs/exec.c:1998 > call_usermodehelper_exec_async+0x2e3/0x580 kernel/umh.c:112 > ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306 > </TASK> > Modules linked in: > CR2: ffffdc0000000000 > ---[ end trace 0000000000000000 ]--- > RIP: 0010:strnlen+0x3b/0x70 lib/string.c:504 > Code: 74 3c 48 bb 00 00 00 00 00 fc ff df 49 89 fc 48 89 f8 eb 09 48 83 c0 01 48 39 e8 74 1e 48 89 c2 48 89 c1 48 c1 ea 03 83 e1 07 <0f> b6 14 1a 38 ca 7f 04 84 d2 75 11 80 38 00 75 d9 4c 29 e0 48 83 > RSP: 0000:ffffc90005c5fe10 EFLAGS: 00010246 > RAX: ffff000000000000 RBX: dffffc0000000000 RCX: 0000000000000000 > RDX: 1fffe00000000000 RSI: 0000000000020000 RDI: ffff000000000000 > RBP: ffff000000020000 R08: 0000000000000005 R09: 0000000000000000 > R10: 0000000000000006 R11: 0000000000000000 R12: ffff000000000000 > R13: ffff88814764cc00 R14: ffff000000000000 R15: ffff88814764cc00 > FS: 0000000000000000(0000) GS:ffff8880b9a00000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: ffffdc0000000000 CR3: 000000000bc8e000 CR4: 00000000003506f0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > ---------------- > Code disassembly (best guess): > 0: 74 3c je 0x3e > 2: 48 bb 00 00 00 00 00 movabs $0xdffffc0000000000,%rbx > 9: fc ff df > c: 49 89 fc mov %rdi,%r12 > f: 48 89 f8 mov %rdi,%rax > 12: eb 09 jmp 0x1d > 14: 48 83 c0 01 add $0x1,%rax > 18: 48 39 e8 cmp %rbp,%rax > 1b: 74 1e je 0x3b > 1d: 48 89 c2 mov %rax,%rdx > 20: 48 89 c1 mov %rax,%rcx > 23: 48 c1 ea 03 shr $0x3,%rdx > 27: 83 e1 07 and $0x7,%ecx > * 2a: 0f b6 14 1a movzbl (%rdx,%rbx,1),%edx <-- trapping instruction > 2e: 38 ca cmp %cl,%dl > 30: 7f 04 jg 0x36 > 32: 84 d2 test %dl,%dl > 34: 75 11 jne 0x47 > 36: 80 38 00 cmpb $0x0,(%rax) > 39: 75 d9 jne 0x14 > 3b: 4c 29 e0 sub %r12,%rax > 3e: 48 rex.W > 3f: 83 .byte 0x83 > > > --- > This report is generated by a bot. It may contain errors. > See https://goo.gl/tpsmEJ for more information about syzbot. > syzbot engineers can be reached at syzkaller@googlegroups.com. > > syzbot will keep track of this issue. See: > https://goo.gl/tpsmEJ#status for how to communicate with syzbot. -- Kees Cook ^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [syzbot] linux-next boot error: BUG: unable to handle kernel paging request in kernel_execve 2022-08-11 15:33 ` Kees Cook @ 2022-08-11 17:39 ` Ira Weiny 2022-08-11 18:51 ` Ira Weiny 0 siblings, 1 reply; 8+ messages in thread From: Ira Weiny @ 2022-08-11 17:39 UTC (permalink / raw) To: Kees Cook Cc: Fabio M. De Francesco, ebiederm, linux-fsdevel, linux-kernel, linux-mm, linux-next, sfr, syzkaller-bugs, viro, syzbot On Thu, Aug 11, 2022 at 08:33:16AM -0700, Kees Cook wrote: > Hi Fabio, > > It seems likely that the kmap change[1] might be causing this crash. Is > there a boot-time setup race between kmap being available and early umh > usage? I don't see how this is a setup problem with the config reported here. CONFIG_64BIT=y ...and HIGHMEM is not set. ...and PREEMPT_RT is not set. So the kmap_local_page() call in that stack should be a page_address() only. I think the issue must be some sort of race which was being prevented because of the preemption and/or pagefault disable built into kmap_atomic(). Is this reproducable? The hunk below will surely fix it but I think the pagefault_disable() is the only thing that is required. It would be nice to test it. Ira diff --git a/fs/exec.c b/fs/exec.c index b51dd14e7388..3da588c858ca 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -640,7 +640,11 @@ int copy_string_kernel(const char *arg, struct linux_binprm *bprm) if (!page) return -E2BIG; flush_arg_page(bprm, pos & PAGE_MASK, page); + preempt_disable(); + pagefault_disable(); memcpy_to_page(page, offset_in_page(pos), arg, bytes_to_copy); + pagefault_enable(); + preempt_enable(); put_arg_page(page); } > > -Kees > > [1] https://git.kernel.org/linus/c6e8e36c6ae4b11bed5643317afb66b6c3cadba8 > > On Thu, Aug 11, 2022 at 12:29:34AM -0700, syzbot wrote: > > Hello, > > > > syzbot found the following issue on: > > > > HEAD commit: bc6c6584ffb2 Add linux-next specific files for 20220810 > > git tree: linux-next > > console output: https://syzkaller.appspot.com/x/log.txt?x=115034c3080000 > > kernel config: https://syzkaller.appspot.com/x/.config?x=5784be4315a4403b > > dashboard link: https://syzkaller.appspot.com/bug?extid=3250d9c8925ef29e975f > > compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2 > > > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > > Reported-by: syzbot+3250d9c8925ef29e975f@syzkaller.appspotmail.com > > > > BUG: unable to handle page fault for address: ffffdc0000000000 > > #PF: supervisor read access in kernel mode > > #PF: error_code(0x0000) - not-present page > > PGD 11826067 P4D 11826067 PUD 0 > > Oops: 0000 [#1] PREEMPT SMP KASAN > > CPU: 0 PID: 1100 Comm: kworker/u4:5 Not tainted 5.19.0-next-20220810-syzkaller #0 > > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/22/2022 > > RIP: 0010:strnlen+0x3b/0x70 lib/string.c:504 > > Code: 74 3c 48 bb 00 00 00 00 00 fc ff df 49 89 fc 48 89 f8 eb 09 48 83 c0 01 48 39 e8 74 1e 48 89 c2 48 89 c1 48 c1 ea 03 83 e1 07 <0f> b6 14 1a 38 ca 7f 04 84 d2 75 11 80 38 00 75 d9 4c 29 e0 48 83 > > RSP: 0000:ffffc90005c5fe10 EFLAGS: 00010246 > > RAX: ffff000000000000 RBX: dffffc0000000000 RCX: 0000000000000000 > > RDX: 1fffe00000000000 RSI: 0000000000020000 RDI: ffff000000000000 > > RBP: ffff000000020000 R08: 0000000000000005 R09: 0000000000000000 > > R10: 0000000000000006 R11: 0000000000000000 R12: ffff000000000000 > > R13: ffff88814764cc00 R14: ffff000000000000 R15: ffff88814764cc00 > > FS: 0000000000000000(0000) GS:ffff8880b9a00000(0000) knlGS:0000000000000000 > > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > CR2: ffffdc0000000000 CR3: 000000000bc8e000 CR4: 00000000003506f0 > > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > > Call Trace: > > <TASK> > > strnlen include/linux/fortify-string.h:119 [inline] > > copy_string_kernel+0x26/0x250 fs/exec.c:616 > > copy_strings_kernel+0xb3/0x190 fs/exec.c:655 > > kernel_execve+0x377/0x500 fs/exec.c:1998 > > call_usermodehelper_exec_async+0x2e3/0x580 kernel/umh.c:112 > > ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306 > > </TASK> > > Modules linked in: > > CR2: ffffdc0000000000 > > ---[ end trace 0000000000000000 ]--- > > RIP: 0010:strnlen+0x3b/0x70 lib/string.c:504 > > Code: 74 3c 48 bb 00 00 00 00 00 fc ff df 49 89 fc 48 89 f8 eb 09 48 83 c0 01 48 39 e8 74 1e 48 89 c2 48 89 c1 48 c1 ea 03 83 e1 07 <0f> b6 14 1a 38 ca 7f 04 84 d2 75 11 80 38 00 75 d9 4c 29 e0 48 83 > > RSP: 0000:ffffc90005c5fe10 EFLAGS: 00010246 > > RAX: ffff000000000000 RBX: dffffc0000000000 RCX: 0000000000000000 > > RDX: 1fffe00000000000 RSI: 0000000000020000 RDI: ffff000000000000 > > RBP: ffff000000020000 R08: 0000000000000005 R09: 0000000000000000 > > R10: 0000000000000006 R11: 0000000000000000 R12: ffff000000000000 > > R13: ffff88814764cc00 R14: ffff000000000000 R15: ffff88814764cc00 > > FS: 0000000000000000(0000) GS:ffff8880b9a00000(0000) knlGS:0000000000000000 > > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > CR2: ffffdc0000000000 CR3: 000000000bc8e000 CR4: 00000000003506f0 > > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > > ---------------- > > Code disassembly (best guess): > > 0: 74 3c je 0x3e > > 2: 48 bb 00 00 00 00 00 movabs $0xdffffc0000000000,%rbx > > 9: fc ff df > > c: 49 89 fc mov %rdi,%r12 > > f: 48 89 f8 mov %rdi,%rax > > 12: eb 09 jmp 0x1d > > 14: 48 83 c0 01 add $0x1,%rax > > 18: 48 39 e8 cmp %rbp,%rax > > 1b: 74 1e je 0x3b > > 1d: 48 89 c2 mov %rax,%rdx > > 20: 48 89 c1 mov %rax,%rcx > > 23: 48 c1 ea 03 shr $0x3,%rdx > > 27: 83 e1 07 and $0x7,%ecx > > * 2a: 0f b6 14 1a movzbl (%rdx,%rbx,1),%edx <-- trapping instruction > > 2e: 38 ca cmp %cl,%dl > > 30: 7f 04 jg 0x36 > > 32: 84 d2 test %dl,%dl > > 34: 75 11 jne 0x47 > > 36: 80 38 00 cmpb $0x0,(%rax) > > 39: 75 d9 jne 0x14 > > 3b: 4c 29 e0 sub %r12,%rax > > 3e: 48 rex.W > > 3f: 83 .byte 0x83 > > > > > > --- > > This report is generated by a bot. It may contain errors. > > See https://goo.gl/tpsmEJ for more information about syzbot. > > syzbot engineers can be reached at syzkaller@googlegroups.com. > > > > syzbot will keep track of this issue. See: > > https://goo.gl/tpsmEJ#status for how to communicate with syzbot. > > -- > Kees Cook ^ permalink raw reply related [flat|nested] 8+ messages in thread
* Re: [syzbot] linux-next boot error: BUG: unable to handle kernel paging request in kernel_execve 2022-08-11 17:39 ` Ira Weiny @ 2022-08-11 18:51 ` Ira Weiny 2022-08-11 21:00 ` Kees Cook 0 siblings, 1 reply; 8+ messages in thread From: Ira Weiny @ 2022-08-11 18:51 UTC (permalink / raw) To: Kees Cook Cc: Fabio M. De Francesco, ebiederm, linux-fsdevel, linux-kernel, linux-mm, linux-next, sfr, syzkaller-bugs, viro, syzbot On Thu, Aug 11, 2022 at 10:39:29AM -0700, Ira wrote: > On Thu, Aug 11, 2022 at 08:33:16AM -0700, Kees Cook wrote: > > Hi Fabio, > > > > It seems likely that the kmap change[1] might be causing this crash. Is > > there a boot-time setup race between kmap being available and early umh > > usage? > > I don't see how this is a setup problem with the config reported here. > > CONFIG_64BIT=y > > ...and HIGHMEM is not set. > ...and PREEMPT_RT is not set. > > So the kmap_local_page() call in that stack should be a page_address() only. > > I think the issue must be some sort of race which was being prevented because > of the preemption and/or pagefault disable built into kmap_atomic(). > > Is this reproducable? > > The hunk below will surely fix it but I think the pagefault_disable() is > the only thing that is required. It would be nice to test it. Fabio and I discussed this. And he also mentioned that pagefault_disable() is all that is required. Do we have a way to test this? Ira > > Ira > > > diff --git a/fs/exec.c b/fs/exec.c > index b51dd14e7388..3da588c858ca 100644 > --- a/fs/exec.c > +++ b/fs/exec.c > @@ -640,7 +640,11 @@ int copy_string_kernel(const char *arg, struct linux_binprm *bprm) > if (!page) > return -E2BIG; > flush_arg_page(bprm, pos & PAGE_MASK, page); > + preempt_disable(); > + pagefault_disable(); > memcpy_to_page(page, offset_in_page(pos), arg, bytes_to_copy); > + pagefault_enable(); > + preempt_enable(); > put_arg_page(page); > } > > > > > > -Kees > > > > [1] https://git.kernel.org/linus/c6e8e36c6ae4b11bed5643317afb66b6c3cadba8 > > > > On Thu, Aug 11, 2022 at 12:29:34AM -0700, syzbot wrote: > > > Hello, > > > > > > syzbot found the following issue on: > > > > > > HEAD commit: bc6c6584ffb2 Add linux-next specific files for 20220810 > > > git tree: linux-next > > > console output: https://syzkaller.appspot.com/x/log.txt?x=115034c3080000 > > > kernel config: https://syzkaller.appspot.com/x/.config?x=5784be4315a4403b > > > dashboard link: https://syzkaller.appspot.com/bug?extid=3250d9c8925ef29e975f > > > compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2 > > > > > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > > > Reported-by: syzbot+3250d9c8925ef29e975f@syzkaller.appspotmail.com > > > > > > BUG: unable to handle page fault for address: ffffdc0000000000 > > > #PF: supervisor read access in kernel mode > > > #PF: error_code(0x0000) - not-present page > > > PGD 11826067 P4D 11826067 PUD 0 > > > Oops: 0000 [#1] PREEMPT SMP KASAN > > > CPU: 0 PID: 1100 Comm: kworker/u4:5 Not tainted 5.19.0-next-20220810-syzkaller #0 > > > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/22/2022 > > > RIP: 0010:strnlen+0x3b/0x70 lib/string.c:504 > > > Code: 74 3c 48 bb 00 00 00 00 00 fc ff df 49 89 fc 48 89 f8 eb 09 48 83 c0 01 48 39 e8 74 1e 48 89 c2 48 89 c1 48 c1 ea 03 83 e1 07 <0f> b6 14 1a 38 ca 7f 04 84 d2 75 11 80 38 00 75 d9 4c 29 e0 48 83 > > > RSP: 0000:ffffc90005c5fe10 EFLAGS: 00010246 > > > RAX: ffff000000000000 RBX: dffffc0000000000 RCX: 0000000000000000 > > > RDX: 1fffe00000000000 RSI: 0000000000020000 RDI: ffff000000000000 > > > RBP: ffff000000020000 R08: 0000000000000005 R09: 0000000000000000 > > > R10: 0000000000000006 R11: 0000000000000000 R12: ffff000000000000 > > > R13: ffff88814764cc00 R14: ffff000000000000 R15: ffff88814764cc00 > > > FS: 0000000000000000(0000) GS:ffff8880b9a00000(0000) knlGS:0000000000000000 > > > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > > CR2: ffffdc0000000000 CR3: 000000000bc8e000 CR4: 00000000003506f0 > > > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > > > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > > > Call Trace: > > > <TASK> > > > strnlen include/linux/fortify-string.h:119 [inline] > > > copy_string_kernel+0x26/0x250 fs/exec.c:616 > > > copy_strings_kernel+0xb3/0x190 fs/exec.c:655 > > > kernel_execve+0x377/0x500 fs/exec.c:1998 > > > call_usermodehelper_exec_async+0x2e3/0x580 kernel/umh.c:112 > > > ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306 > > > </TASK> > > > Modules linked in: > > > CR2: ffffdc0000000000 > > > ---[ end trace 0000000000000000 ]--- > > > RIP: 0010:strnlen+0x3b/0x70 lib/string.c:504 > > > Code: 74 3c 48 bb 00 00 00 00 00 fc ff df 49 89 fc 48 89 f8 eb 09 48 83 c0 01 48 39 e8 74 1e 48 89 c2 48 89 c1 48 c1 ea 03 83 e1 07 <0f> b6 14 1a 38 ca 7f 04 84 d2 75 11 80 38 00 75 d9 4c 29 e0 48 83 > > > RSP: 0000:ffffc90005c5fe10 EFLAGS: 00010246 > > > RAX: ffff000000000000 RBX: dffffc0000000000 RCX: 0000000000000000 > > > RDX: 1fffe00000000000 RSI: 0000000000020000 RDI: ffff000000000000 > > > RBP: ffff000000020000 R08: 0000000000000005 R09: 0000000000000000 > > > R10: 0000000000000006 R11: 0000000000000000 R12: ffff000000000000 > > > R13: ffff88814764cc00 R14: ffff000000000000 R15: ffff88814764cc00 > > > FS: 0000000000000000(0000) GS:ffff8880b9a00000(0000) knlGS:0000000000000000 > > > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > > CR2: ffffdc0000000000 CR3: 000000000bc8e000 CR4: 00000000003506f0 > > > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > > > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > > > ---------------- > > > Code disassembly (best guess): > > > 0: 74 3c je 0x3e > > > 2: 48 bb 00 00 00 00 00 movabs $0xdffffc0000000000,%rbx > > > 9: fc ff df > > > c: 49 89 fc mov %rdi,%r12 > > > f: 48 89 f8 mov %rdi,%rax > > > 12: eb 09 jmp 0x1d > > > 14: 48 83 c0 01 add $0x1,%rax > > > 18: 48 39 e8 cmp %rbp,%rax > > > 1b: 74 1e je 0x3b > > > 1d: 48 89 c2 mov %rax,%rdx > > > 20: 48 89 c1 mov %rax,%rcx > > > 23: 48 c1 ea 03 shr $0x3,%rdx > > > 27: 83 e1 07 and $0x7,%ecx > > > * 2a: 0f b6 14 1a movzbl (%rdx,%rbx,1),%edx <-- trapping instruction > > > 2e: 38 ca cmp %cl,%dl > > > 30: 7f 04 jg 0x36 > > > 32: 84 d2 test %dl,%dl > > > 34: 75 11 jne 0x47 > > > 36: 80 38 00 cmpb $0x0,(%rax) > > > 39: 75 d9 jne 0x14 > > > 3b: 4c 29 e0 sub %r12,%rax > > > 3e: 48 rex.W > > > 3f: 83 .byte 0x83 > > > > > > > > > --- > > > This report is generated by a bot. It may contain errors. > > > See https://goo.gl/tpsmEJ for more information about syzbot. > > > syzbot engineers can be reached at syzkaller@googlegroups.com. > > > > > > syzbot will keep track of this issue. See: > > > https://goo.gl/tpsmEJ#status for how to communicate with syzbot. > > > > -- > > Kees Cook ^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [syzbot] linux-next boot error: BUG: unable to handle kernel paging request in kernel_execve 2022-08-11 18:51 ` Ira Weiny @ 2022-08-11 21:00 ` Kees Cook 2022-08-12 0:11 ` Ira Weiny 0 siblings, 1 reply; 8+ messages in thread From: Kees Cook @ 2022-08-11 21:00 UTC (permalink / raw) To: Ira Weiny Cc: Fabio M. De Francesco, ebiederm, linux-fsdevel, linux-kernel, linux-mm, linux-next, sfr, syzkaller-bugs, viro, syzbot On Thu, Aug 11, 2022 at 11:51:34AM -0700, Ira Weiny wrote: > On Thu, Aug 11, 2022 at 10:39:29AM -0700, Ira wrote: > > On Thu, Aug 11, 2022 at 08:33:16AM -0700, Kees Cook wrote: > > > Hi Fabio, > > > > > > It seems likely that the kmap change[1] might be causing this crash. Is > > > there a boot-time setup race between kmap being available and early umh > > > usage? > > > > I don't see how this is a setup problem with the config reported here. > > > > CONFIG_64BIT=y > > > > ...and HIGHMEM is not set. > > ...and PREEMPT_RT is not set. > > > > So the kmap_local_page() call in that stack should be a page_address() only. > > > > I think the issue must be some sort of race which was being prevented because > > of the preemption and/or pagefault disable built into kmap_atomic(). > > > > Is this reproducable? > > > > The hunk below will surely fix it but I think the pagefault_disable() is > > the only thing that is required. It would be nice to test it. > > Fabio and I discussed this. And he also mentioned that pagefault_disable() is > all that is required. Okay, sounds good. > Do we have a way to test this? It doesn't look like syzbot has a reproducer yet, so its patch testing system[1] will not work. But if you can send me a patch, I could land it in -next and we could see if the reproduction frequency drops to zero. (Looking at the dashboard, it's seen 2 crashes, most recently 8 hours ago.) -Kees [1] https://github.com/google/syzkaller/blob/master/docs/syzbot.md#testing-patches > > > > syzbot found the following issue on: > > > > > > > > HEAD commit: bc6c6584ffb2 Add linux-next specific files for 20220810 > > > > git tree: linux-next > > > > console output: https://syzkaller.appspot.com/x/log.txt?x=115034c3080000 > > > > kernel config: https://syzkaller.appspot.com/x/.config?x=5784be4315a4403b > > > > dashboard link: https://syzkaller.appspot.com/bug?extid=3250d9c8925ef29e975f > > > > compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2 > > > > > > > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > > > > Reported-by: syzbot+3250d9c8925ef29e975f@syzkaller.appspotmail.com > > > > > > > > BUG: unable to handle page fault for address: ffffdc0000000000 > > > > #PF: supervisor read access in kernel mode > > > > #PF: error_code(0x0000) - not-present page > > > > PGD 11826067 P4D 11826067 PUD 0 > > > > Oops: 0000 [#1] PREEMPT SMP KASAN > > > > CPU: 0 PID: 1100 Comm: kworker/u4:5 Not tainted 5.19.0-next-20220810-syzkaller #0 > > > > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/22/2022 > > > > RIP: 0010:strnlen+0x3b/0x70 lib/string.c:504 > > > > Code: 74 3c 48 bb 00 00 00 00 00 fc ff df 49 89 fc 48 89 f8 eb 09 48 83 c0 01 48 39 e8 74 1e 48 89 c2 48 89 c1 48 c1 ea 03 83 e1 07 <0f> b6 14 1a 38 ca 7f 04 84 d2 75 11 80 38 00 75 d9 4c 29 e0 48 83 > > > > RSP: 0000:ffffc90005c5fe10 EFLAGS: 00010246 > > > > RAX: ffff000000000000 RBX: dffffc0000000000 RCX: 0000000000000000 > > > > RDX: 1fffe00000000000 RSI: 0000000000020000 RDI: ffff000000000000 > > > > RBP: ffff000000020000 R08: 0000000000000005 R09: 0000000000000000 > > > > R10: 0000000000000006 R11: 0000000000000000 R12: ffff000000000000 > > > > R13: ffff88814764cc00 R14: ffff000000000000 R15: ffff88814764cc00 > > > > FS: 0000000000000000(0000) GS:ffff8880b9a00000(0000) knlGS:0000000000000000 > > > > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > > > CR2: ffffdc0000000000 CR3: 000000000bc8e000 CR4: 00000000003506f0 > > > > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > > > > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > > > > Call Trace: > > > > <TASK> > > > > strnlen include/linux/fortify-string.h:119 [inline] > > > > copy_string_kernel+0x26/0x250 fs/exec.c:616 > > > > copy_strings_kernel+0xb3/0x190 fs/exec.c:655 > > > > kernel_execve+0x377/0x500 fs/exec.c:1998 > > > > call_usermodehelper_exec_async+0x2e3/0x580 kernel/umh.c:112 > > > > ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306 > > > > </TASK> > [...] > > > > --- > > > > This report is generated by a bot. It may contain errors. > > > > See https://goo.gl/tpsmEJ for more information about syzbot. > > > > syzbot engineers can be reached at syzkaller@googlegroups.com. > > > > > > > > syzbot will keep track of this issue. See: > > > > https://goo.gl/tpsmEJ#status for how to communicate with syzbot. -- Kees Cook ^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [syzbot] linux-next boot error: BUG: unable to handle kernel paging request in kernel_execve 2022-08-11 21:00 ` Kees Cook @ 2022-08-12 0:11 ` Ira Weiny 2022-08-12 9:29 ` Dmitry Vyukov 0 siblings, 1 reply; 8+ messages in thread From: Ira Weiny @ 2022-08-12 0:11 UTC (permalink / raw) To: Kees Cook Cc: Fabio M. De Francesco, ebiederm, linux-fsdevel, linux-kernel, linux-mm, linux-next, sfr, syzkaller-bugs, viro, syzbot On Thu, Aug 11, 2022 at 02:00:59PM -0700, Kees Cook wrote: > On Thu, Aug 11, 2022 at 11:51:34AM -0700, Ira Weiny wrote: > > On Thu, Aug 11, 2022 at 10:39:29AM -0700, Ira wrote: > > > On Thu, Aug 11, 2022 at 08:33:16AM -0700, Kees Cook wrote: > > > > Hi Fabio, > > > > > > > > It seems likely that the kmap change[1] might be causing this crash. Is > > > > there a boot-time setup race between kmap being available and early umh > > > > usage? > > > > > > I don't see how this is a setup problem with the config reported here. > > > > > > CONFIG_64BIT=y > > > > > > ...and HIGHMEM is not set. > > > ...and PREEMPT_RT is not set. > > > > > > So the kmap_local_page() call in that stack should be a page_address() only. > > > > > > I think the issue must be some sort of race which was being prevented because > > > of the preemption and/or pagefault disable built into kmap_atomic(). > > > > > > Is this reproducable? > > > > > > The hunk below will surely fix it but I think the pagefault_disable() is > > > the only thing that is required. It would be nice to test it. > > > > Fabio and I discussed this. And he also mentioned that pagefault_disable() is > > all that is required. > > Okay, sounds good. > > > Do we have a way to test this? > > It doesn't look like syzbot has a reproducer yet, so its patch testing > system[1] will not work. But if you can send me a patch, I could land it > in -next and we could see if the reproduction frequency drops to zero. > (Looking at the dashboard, it's seen 2 crashes, most recently 8 hours > ago.) Patch sent. https://lore.kernel.org/lkml/20220812000919.408614-1-ira.weiny@intel.com/ But I'm more confused after looking at this again. Ira > > -Kees > > [1] https://github.com/google/syzkaller/blob/master/docs/syzbot.md#testing-patches > > > > > > syzbot found the following issue on: > > > > > > > > > > HEAD commit: bc6c6584ffb2 Add linux-next specific files for 20220810 > > > > > git tree: linux-next > > > > > console output: https://syzkaller.appspot.com/x/log.txt?x=115034c3080000 > > > > > kernel config: https://syzkaller.appspot.com/x/.config?x=5784be4315a4403b > > > > > dashboard link: https://syzkaller.appspot.com/bug?extid=3250d9c8925ef29e975f > > > > > compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2 > > > > > > > > > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > > > > > Reported-by: syzbot+3250d9c8925ef29e975f@syzkaller.appspotmail.com > > > > > > > > > > BUG: unable to handle page fault for address: ffffdc0000000000 > > > > > #PF: supervisor read access in kernel mode > > > > > #PF: error_code(0x0000) - not-present page > > > > > PGD 11826067 P4D 11826067 PUD 0 > > > > > Oops: 0000 [#1] PREEMPT SMP KASAN > > > > > CPU: 0 PID: 1100 Comm: kworker/u4:5 Not tainted 5.19.0-next-20220810-syzkaller #0 > > > > > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/22/2022 > > > > > RIP: 0010:strnlen+0x3b/0x70 lib/string.c:504 > > > > > Code: 74 3c 48 bb 00 00 00 00 00 fc ff df 49 89 fc 48 89 f8 eb 09 48 83 c0 01 48 39 e8 74 1e 48 89 c2 48 89 c1 48 c1 ea 03 83 e1 07 <0f> b6 14 1a 38 ca 7f 04 84 d2 75 11 80 38 00 75 d9 4c 29 e0 48 83 > > > > > RSP: 0000:ffffc90005c5fe10 EFLAGS: 00010246 > > > > > RAX: ffff000000000000 RBX: dffffc0000000000 RCX: 0000000000000000 > > > > > RDX: 1fffe00000000000 RSI: 0000000000020000 RDI: ffff000000000000 > > > > > RBP: ffff000000020000 R08: 0000000000000005 R09: 0000000000000000 > > > > > R10: 0000000000000006 R11: 0000000000000000 R12: ffff000000000000 > > > > > R13: ffff88814764cc00 R14: ffff000000000000 R15: ffff88814764cc00 > > > > > FS: 0000000000000000(0000) GS:ffff8880b9a00000(0000) knlGS:0000000000000000 > > > > > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > > > > CR2: ffffdc0000000000 CR3: 000000000bc8e000 CR4: 00000000003506f0 > > > > > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > > > > > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > > > > > Call Trace: > > > > > <TASK> > > > > > strnlen include/linux/fortify-string.h:119 [inline] > > > > > copy_string_kernel+0x26/0x250 fs/exec.c:616 > > > > > copy_strings_kernel+0xb3/0x190 fs/exec.c:655 > > > > > kernel_execve+0x377/0x500 fs/exec.c:1998 > > > > > call_usermodehelper_exec_async+0x2e3/0x580 kernel/umh.c:112 > > > > > ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306 > > > > > </TASK> > > [...] > > > > > --- > > > > > This report is generated by a bot. It may contain errors. > > > > > See https://goo.gl/tpsmEJ for more information about syzbot. > > > > > syzbot engineers can be reached at syzkaller@googlegroups.com. > > > > > > > > > > syzbot will keep track of this issue. See: > > > > > https://goo.gl/tpsmEJ#status for how to communicate with syzbot. > > -- > Kees Cook ^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [syzbot] linux-next boot error: BUG: unable to handle kernel paging request in kernel_execve 2022-08-12 0:11 ` Ira Weiny @ 2022-08-12 9:29 ` Dmitry Vyukov 2022-08-12 18:44 ` Kees Cook 0 siblings, 1 reply; 8+ messages in thread From: Dmitry Vyukov @ 2022-08-12 9:29 UTC (permalink / raw) To: Ira Weiny Cc: Kees Cook, Fabio M. De Francesco, ebiederm, linux-fsdevel, linux-kernel, linux-mm, linux-next, sfr, syzkaller-bugs, viro, syzbot On Fri, 12 Aug 2022 at 02:11, Ira Weiny <ira.weiny@intel.com> wrote: > > On Thu, Aug 11, 2022 at 02:00:59PM -0700, Kees Cook wrote: > > On Thu, Aug 11, 2022 at 11:51:34AM -0700, Ira Weiny wrote: > > > On Thu, Aug 11, 2022 at 10:39:29AM -0700, Ira wrote: > > > > On Thu, Aug 11, 2022 at 08:33:16AM -0700, Kees Cook wrote: > > > > > Hi Fabio, > > > > > > > > > > It seems likely that the kmap change[1] might be causing this crash. Is > > > > > there a boot-time setup race between kmap being available and early umh > > > > > usage? > > > > > > > > I don't see how this is a setup problem with the config reported here. > > > > > > > > CONFIG_64BIT=y > > > > > > > > ...and HIGHMEM is not set. > > > > ...and PREEMPT_RT is not set. > > > > > > > > So the kmap_local_page() call in that stack should be a page_address() only. > > > > > > > > I think the issue must be some sort of race which was being prevented because > > > > of the preemption and/or pagefault disable built into kmap_atomic(). > > > > > > > > Is this reproducable? > > > > > > > > The hunk below will surely fix it but I think the pagefault_disable() is > > > > the only thing that is required. It would be nice to test it. > > > > > > Fabio and I discussed this. And he also mentioned that pagefault_disable() is > > > all that is required. > > > > Okay, sounds good. > > > > > Do we have a way to test this? > > > > It doesn't look like syzbot has a reproducer yet, so its patch testing > > system[1] will not work. But if you can send me a patch, I could land it > > in -next and we could see if the reproduction frequency drops to zero. > > (Looking at the dashboard, it's seen 2 crashes, most recently 8 hours > > ago.) > > Patch sent. > > https://lore.kernel.org/lkml/20220812000919.408614-1-ira.weiny@intel.com/ > > But I'm more confused after looking at this again. There is splat of random crashes in linux-next happened at the same time: https://groups.google.com/g/syzkaller-bugs/search?q=%22linux-next%20boot%20error%3A%22 There are 10 different crashes in completely random places. I would assume they have the same root cause, some silent memory corruption or something similar. > > [1] https://github.com/google/syzkaller/blob/master/docs/syzbot.md#testing-patches > > > > > > > > syzbot found the following issue on: > > > > > > > > > > > > HEAD commit: bc6c6584ffb2 Add linux-next specific files for 20220810 > > > > > > git tree: linux-next > > > > > > console output: https://syzkaller.appspot.com/x/log.txt?x=115034c3080000 > > > > > > kernel config: https://syzkaller.appspot.com/x/.config?x=5784be4315a4403b > > > > > > dashboard link: https://syzkaller.appspot.com/bug?extid=3250d9c8925ef29e975f > > > > > > compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2 > > > > > > > > > > > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > > > > > > Reported-by: syzbot+3250d9c8925ef29e975f@syzkaller.appspotmail.com > > > > > > > > > > > > BUG: unable to handle page fault for address: ffffdc0000000000 > > > > > > #PF: supervisor read access in kernel mode > > > > > > #PF: error_code(0x0000) - not-present page > > > > > > PGD 11826067 P4D 11826067 PUD 0 > > > > > > Oops: 0000 [#1] PREEMPT SMP KASAN > > > > > > CPU: 0 PID: 1100 Comm: kworker/u4:5 Not tainted 5.19.0-next-20220810-syzkaller #0 > > > > > > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/22/2022 > > > > > > RIP: 0010:strnlen+0x3b/0x70 lib/string.c:504 > > > > > > Code: 74 3c 48 bb 00 00 00 00 00 fc ff df 49 89 fc 48 89 f8 eb 09 48 83 c0 01 48 39 e8 74 1e 48 89 c2 48 89 c1 48 c1 ea 03 83 e1 07 <0f> b6 14 1a 38 ca 7f 04 84 d2 75 11 80 38 00 75 d9 4c 29 e0 48 83 > > > > > > RSP: 0000:ffffc90005c5fe10 EFLAGS: 00010246 > > > > > > RAX: ffff000000000000 RBX: dffffc0000000000 RCX: 0000000000000000 > > > > > > RDX: 1fffe00000000000 RSI: 0000000000020000 RDI: ffff000000000000 > > > > > > RBP: ffff000000020000 R08: 0000000000000005 R09: 0000000000000000 > > > > > > R10: 0000000000000006 R11: 0000000000000000 R12: ffff000000000000 > > > > > > R13: ffff88814764cc00 R14: ffff000000000000 R15: ffff88814764cc00 > > > > > > FS: 0000000000000000(0000) GS:ffff8880b9a00000(0000) knlGS:0000000000000000 > > > > > > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > > > > > CR2: ffffdc0000000000 CR3: 000000000bc8e000 CR4: 00000000003506f0 > > > > > > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > > > > > > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > > > > > > Call Trace: > > > > > > <TASK> > > > > > > strnlen include/linux/fortify-string.h:119 [inline] > > > > > > copy_string_kernel+0x26/0x250 fs/exec.c:616 > > > > > > copy_strings_kernel+0xb3/0x190 fs/exec.c:655 > > > > > > kernel_execve+0x377/0x500 fs/exec.c:1998 > > > > > > call_usermodehelper_exec_async+0x2e3/0x580 kernel/umh.c:112 > > > > > > ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306 > > > > > > </TASK> > > > [...] > > > > > > --- > > > > > > This report is generated by a bot. It may contain errors. > > > > > > See https://goo.gl/tpsmEJ for more information about syzbot. > > > > > > syzbot engineers can be reached at syzkaller@googlegroups.com. > > > > > > > > > > > > syzbot will keep track of this issue. See: > > > > > > https://goo.gl/tpsmEJ#status for how to communicate with syzbot. > > > > -- > > Kees Cook > > -- > You received this message because you are subscribed to the Google Groups "syzkaller-bugs" group. > To unsubscribe from this group and stop receiving emails from it, send an email to syzkaller-bugs+unsubscribe@googlegroups.com. > To view this discussion on the web visit https://groups.google.com/d/msgid/syzkaller-bugs/YvWaqhLGsBp9ynIq%40iweiny-desk3. ^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [syzbot] linux-next boot error: BUG: unable to handle kernel paging request in kernel_execve 2022-08-12 9:29 ` Dmitry Vyukov @ 2022-08-12 18:44 ` Kees Cook 0 siblings, 0 replies; 8+ messages in thread From: Kees Cook @ 2022-08-12 18:44 UTC (permalink / raw) To: Dmitry Vyukov Cc: Ira Weiny, Fabio M. De Francesco, ebiederm, linux-fsdevel, linux-kernel, linux-mm, linux-next, sfr, syzkaller-bugs, viro, syzbot On Fri, Aug 12, 2022 at 11:29:44AM +0200, Dmitry Vyukov wrote: > On Fri, 12 Aug 2022 at 02:11, Ira Weiny <ira.weiny@intel.com> wrote: > > > > On Thu, Aug 11, 2022 at 02:00:59PM -0700, Kees Cook wrote: > > > On Thu, Aug 11, 2022 at 11:51:34AM -0700, Ira Weiny wrote: > > > > On Thu, Aug 11, 2022 at 10:39:29AM -0700, Ira wrote: > > > > > On Thu, Aug 11, 2022 at 08:33:16AM -0700, Kees Cook wrote: > > > > > > Hi Fabio, > > > > > > > > > > > > It seems likely that the kmap change[1] might be causing this crash. Is > > > > > > there a boot-time setup race between kmap being available and early umh > > > > > > usage? > > > > > > > > > > I don't see how this is a setup problem with the config reported here. > > > > > > > > > > CONFIG_64BIT=y > > > > > > > > > > ...and HIGHMEM is not set. > > > > > ...and PREEMPT_RT is not set. > > > > > > > > > > So the kmap_local_page() call in that stack should be a page_address() only. > > > > > > > > > > I think the issue must be some sort of race which was being prevented because > > > > > of the preemption and/or pagefault disable built into kmap_atomic(). > > > > > > > > > > Is this reproducable? > > > > > > > > > > The hunk below will surely fix it but I think the pagefault_disable() is > > > > > the only thing that is required. It would be nice to test it. > > > > > > > > Fabio and I discussed this. And he also mentioned that pagefault_disable() is > > > > all that is required. > > > > > > Okay, sounds good. > > > > > > > Do we have a way to test this? > > > > > > It doesn't look like syzbot has a reproducer yet, so its patch testing > > > system[1] will not work. But if you can send me a patch, I could land it > > > in -next and we could see if the reproduction frequency drops to zero. > > > (Looking at the dashboard, it's seen 2 crashes, most recently 8 hours > > > ago.) > > > > Patch sent. > > > > https://lore.kernel.org/lkml/20220812000919.408614-1-ira.weiny@intel.com/ Thank you! > > > > But I'm more confused after looking at this again. > > There is splat of random crashes in linux-next happened at the same time: > > https://groups.google.com/g/syzkaller-bugs/search?q=%22linux-next%20boot%20error%3A%22 > > There are 10 different crashes in completely random places. > I would assume they have the same root cause, some silent memory > corruption or something similar. Yeah, I noticed the crashes stopped "on their own", so I think I'll wait a bit more, and if it start back up, we can try Ira's patch, though I'd agree with the assessment that it looks like it shouldn't be needed. -Kees -- Kees Cook ^ permalink raw reply [flat|nested] 8+ messages in thread
end of thread, other threads:[~2022-08-12 18:44 UTC | newest] Thread overview: 8+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2022-08-11 7:29 [syzbot] linux-next boot error: BUG: unable to handle kernel paging request in kernel_execve syzbot 2022-08-11 15:33 ` Kees Cook 2022-08-11 17:39 ` Ira Weiny 2022-08-11 18:51 ` Ira Weiny 2022-08-11 21:00 ` Kees Cook 2022-08-12 0:11 ` Ira Weiny 2022-08-12 9:29 ` Dmitry Vyukov 2022-08-12 18:44 ` Kees Cook
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