* [PATCH 0/2] fix parsing of reboot= cmdline @ 2020-10-16 18:09 Matteo Croce 2020-10-16 18:09 ` [PATCH 1/2] reboot: fix overflow parsing reboot cpu number Matteo Croce 2020-10-16 18:09 ` [PATCH 2/2] reboot: fix parsing of " Matteo Croce 0 siblings, 2 replies; 10+ messages in thread From: Matteo Croce @ 2020-10-16 18:09 UTC (permalink / raw) To: linux-kernel Cc: Guenter Roeck, Petr Mladek, Arnd Bergmann, Mike Rapoport, Kees Cook, Pavel Tatashin, Robin Holt, Fabian Frederick, stable From: Matteo Croce <mcroce@microsoft.com> The parsing of the reboot= cmdline has two major errors: - a missing bound check can crash the system on reboot - parsing of the cpu number only works if specified last Fix both, along with a small code refactor. Matteo Croce (2): reboot: fix overflow parsing reboot cpu number reboot: fix parsing of reboot cpu number kernel/reboot.c | 24 +++++++++++++----------- 1 file changed, 13 insertions(+), 11 deletions(-) -- 2.26.2 ^ permalink raw reply [flat|nested] 10+ messages in thread
* [PATCH 1/2] reboot: fix overflow parsing reboot cpu number 2020-10-16 18:09 [PATCH 0/2] fix parsing of reboot= cmdline Matteo Croce @ 2020-10-16 18:09 ` Matteo Croce 2020-10-16 19:25 ` Kees Cook ` (2 more replies) 2020-10-16 18:09 ` [PATCH 2/2] reboot: fix parsing of " Matteo Croce 1 sibling, 3 replies; 10+ messages in thread From: Matteo Croce @ 2020-10-16 18:09 UTC (permalink / raw) To: linux-kernel Cc: Guenter Roeck, Petr Mladek, Arnd Bergmann, Mike Rapoport, Kees Cook, Pavel Tatashin, Robin Holt, Fabian Frederick, stable From: Matteo Croce <mcroce@microsoft.com> Limit the CPU number to num_possible_cpus(), because setting it to a value lower than INT_MAX but higher than NR_CPUS produces the following error on reboot and shutdown: BUG: unable to handle page fault for address: ffffffff90ab1bb0 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 1c09067 P4D 1c09067 PUD 1c0a063 PMD 0 Oops: 0000 [#1] SMP CPU: 1 PID: 1 Comm: systemd-shutdow Not tainted 5.9.0-rc8-kvm #110 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.13.0-2.fc32 04/01/2014 RIP: 0010:migrate_to_reboot_cpu+0xe/0x60 Code: ea ea 00 48 89 fa 48 c7 c7 30 57 f1 81 e9 fa ef ff ff 66 2e 0f 1f 84 00 00 00 00 00 53 8b 1d d5 ea ea 00 e8 14 33 fe ff 89 da <48> 0f a3 15 ea fc bd 00 48 89 d0 73 29 89 c2 c1 e8 06 65 48 8b 3c RSP: 0018:ffffc90000013e08 EFLAGS: 00010246 RAX: ffff88801f0a0000 RBX: 0000000077359400 RCX: 0000000000000000 RDX: 0000000077359400 RSI: 0000000000000002 RDI: ffffffff81c199e0 RBP: ffffffff81c1e3c0 R08: ffff88801f41f000 R09: ffffffff81c1e348 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 R13: 00007f32bedf8830 R14: 00000000fee1dead R15: 0000000000000000 FS: 00007f32bedf8980(0000) GS:ffff88801f480000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffffff90ab1bb0 CR3: 000000001d057000 CR4: 00000000000006a0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: __do_sys_reboot.cold+0x34/0x5b ? vfs_writev+0x92/0xc0 ? do_writev+0x52/0xd0 do_syscall_64+0x2d/0x40 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x7f32bfaaecd3 Code: 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 89 fa be 69 19 12 28 bf ad de e1 fe b8 a9 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 05 c3 0f 1f 40 00 48 8b 15 89 81 0c 00 f7 d8 RSP: 002b:00007fff6265fb58 EFLAGS: 00000202 ORIG_RAX: 00000000000000a9 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f32bfaaecd3 RDX: 0000000001234567 RSI: 0000000028121969 RDI: 00000000fee1dead RBP: 0000000000000000 R08: 0000000000008020 R09: 00007fff6265ef60 R10: 00007f32bedf8830 R11: 0000000000000202 R12: 0000000000000000 R13: 0000557bba2c51c0 R14: 0000000000000000 R15: 00007fff6265fbc8 CR2: ffffffff90ab1bb0 ---[ end trace b813e80157136563 ]--- RIP: 0010:migrate_to_reboot_cpu+0xe/0x60 Code: ea ea 00 48 89 fa 48 c7 c7 30 57 f1 81 e9 fa ef ff ff 66 2e 0f 1f 84 00 00 00 00 00 53 8b 1d d5 ea ea 00 e8 14 33 fe ff 89 da <48> 0f a3 15 ea fc bd 00 48 89 d0 73 29 89 c2 c1 e8 06 65 48 8b 3c RSP: 0018:ffffc90000013e08 EFLAGS: 00010246 RAX: ffff88801f0a0000 RBX: 0000000077359400 RCX: 0000000000000000 RDX: 0000000077359400 RSI: 0000000000000002 RDI: ffffffff81c199e0 RBP: ffffffff81c1e3c0 R08: ffff88801f41f000 R09: ffffffff81c1e348 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 R13: 00007f32bedf8830 R14: 00000000fee1dead R15: 0000000000000000 FS: 00007f32bedf8980(0000) GS:ffff88801f480000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffffff90ab1bb0 CR3: 000000001d057000 CR4: 00000000000006a0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000009 Kernel Offset: disabled ---[ end Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000009 ]--- Fixes: 1b3a5d02ee07 ("reboot: move arch/x86 reboot= handling to generic kernel") Signed-off-by: Matteo Croce <mcroce@microsoft.com> --- kernel/reboot.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/kernel/reboot.c b/kernel/reboot.c index e7b78d5ae1ab..c4e7965c39b9 100644 --- a/kernel/reboot.c +++ b/kernel/reboot.c @@ -558,11 +558,19 @@ static int __init reboot_setup(char *str) rc = kstrtoint(str+1, 0, &reboot_cpu); if (rc) return rc; + if (reboot_cpu >= num_possible_cpus()) { + reboot_cpu = 0; + return -ERANGE; + } } else if (str[1] == 'm' && str[2] == 'p' && isdigit(*(str+3))) { rc = kstrtoint(str+3, 0, &reboot_cpu); if (rc) return rc; + if (reboot_cpu >= num_possible_cpus()) { + reboot_cpu = 0; + return -ERANGE; + } } else *mode = REBOOT_SOFT; break; -- 2.26.2 ^ permalink raw reply related [flat|nested] 10+ messages in thread
* Re: [PATCH 1/2] reboot: fix overflow parsing reboot cpu number 2020-10-16 18:09 ` [PATCH 1/2] reboot: fix overflow parsing reboot cpu number Matteo Croce @ 2020-10-16 19:25 ` Kees Cook 2020-10-16 19:45 ` Pavel Tatashin 2020-10-19 13:18 ` Petr Mladek 2 siblings, 0 replies; 10+ messages in thread From: Kees Cook @ 2020-10-16 19:25 UTC (permalink / raw) To: Matteo Croce Cc: linux-kernel, Guenter Roeck, Petr Mladek, Arnd Bergmann, Mike Rapoport, Pavel Tatashin, Robin Holt, Fabian Frederick, stable On Fri, Oct 16, 2020 at 08:09:06PM +0200, Matteo Croce wrote: > From: Matteo Croce <mcroce@microsoft.com> > > Limit the CPU number to num_possible_cpus(), because setting it > to a value lower than INT_MAX but higher than NR_CPUS produces the > following error on reboot and shutdown: > > BUG: unable to handle page fault for address: ffffffff90ab1bb0 > #PF: supervisor read access in kernel mode > #PF: error_code(0x0000) - not-present page > PGD 1c09067 P4D 1c09067 PUD 1c0a063 PMD 0 > Oops: 0000 [#1] SMP > CPU: 1 PID: 1 Comm: systemd-shutdow Not tainted 5.9.0-rc8-kvm #110 > Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.13.0-2.fc32 04/01/2014 > RIP: 0010:migrate_to_reboot_cpu+0xe/0x60 > Code: ea ea 00 48 89 fa 48 c7 c7 30 57 f1 81 e9 fa ef ff ff 66 2e 0f 1f 84 00 00 00 00 00 53 8b 1d d5 ea ea 00 e8 14 33 fe ff 89 da <48> 0f a3 15 ea fc bd 00 48 89 d0 73 29 89 c2 c1 e8 06 65 48 8b 3c > RSP: 0018:ffffc90000013e08 EFLAGS: 00010246 > RAX: ffff88801f0a0000 RBX: 0000000077359400 RCX: 0000000000000000 > RDX: 0000000077359400 RSI: 0000000000000002 RDI: ffffffff81c199e0 > RBP: ffffffff81c1e3c0 R08: ffff88801f41f000 R09: ffffffff81c1e348 > R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 > R13: 00007f32bedf8830 R14: 00000000fee1dead R15: 0000000000000000 > FS: 00007f32bedf8980(0000) GS:ffff88801f480000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: ffffffff90ab1bb0 CR3: 000000001d057000 CR4: 00000000000006a0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > Call Trace: > __do_sys_reboot.cold+0x34/0x5b > ? vfs_writev+0x92/0xc0 > ? do_writev+0x52/0xd0 > do_syscall_64+0x2d/0x40 > entry_SYSCALL_64_after_hwframe+0x44/0xa9 > RIP: 0033:0x7f32bfaaecd3 > Code: 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 89 fa be 69 19 12 28 bf ad de e1 fe b8 a9 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 05 c3 0f 1f 40 00 48 8b 15 89 81 0c 00 f7 d8 > RSP: 002b:00007fff6265fb58 EFLAGS: 00000202 ORIG_RAX: 00000000000000a9 > RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f32bfaaecd3 > RDX: 0000000001234567 RSI: 0000000028121969 RDI: 00000000fee1dead > RBP: 0000000000000000 R08: 0000000000008020 R09: 00007fff6265ef60 > R10: 00007f32bedf8830 R11: 0000000000000202 R12: 0000000000000000 > R13: 0000557bba2c51c0 R14: 0000000000000000 R15: 00007fff6265fbc8 > CR2: ffffffff90ab1bb0 > ---[ end trace b813e80157136563 ]--- > RIP: 0010:migrate_to_reboot_cpu+0xe/0x60 > Code: ea ea 00 48 89 fa 48 c7 c7 30 57 f1 81 e9 fa ef ff ff 66 2e 0f 1f 84 00 00 00 00 00 53 8b 1d d5 ea ea 00 e8 14 33 fe ff 89 da <48> 0f a3 15 ea fc bd 00 48 89 d0 73 29 89 c2 c1 e8 06 65 48 8b 3c > RSP: 0018:ffffc90000013e08 EFLAGS: 00010246 > RAX: ffff88801f0a0000 RBX: 0000000077359400 RCX: 0000000000000000 > RDX: 0000000077359400 RSI: 0000000000000002 RDI: ffffffff81c199e0 > RBP: ffffffff81c1e3c0 R08: ffff88801f41f000 R09: ffffffff81c1e348 > R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 > R13: 00007f32bedf8830 R14: 00000000fee1dead R15: 0000000000000000 > FS: 00007f32bedf8980(0000) GS:ffff88801f480000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: ffffffff90ab1bb0 CR3: 000000001d057000 CR4: 00000000000006a0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000009 > Kernel Offset: disabled > ---[ end Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000009 ]--- > > Fixes: 1b3a5d02ee07 ("reboot: move arch/x86 reboot= handling to generic kernel") > Signed-off-by: Matteo Croce <mcroce@microsoft.com> Reviewed-by: Kees Cook <keescook@chromium.org> -- Kees Cook ^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH 1/2] reboot: fix overflow parsing reboot cpu number 2020-10-16 18:09 ` [PATCH 1/2] reboot: fix overflow parsing reboot cpu number Matteo Croce 2020-10-16 19:25 ` Kees Cook @ 2020-10-16 19:45 ` Pavel Tatashin 2020-10-19 13:18 ` Petr Mladek 2 siblings, 0 replies; 10+ messages in thread From: Pavel Tatashin @ 2020-10-16 19:45 UTC (permalink / raw) To: Matteo Croce Cc: LKML, Guenter Roeck, Petr Mladek, Arnd Bergmann, Mike Rapoport, Kees Cook, Robin Holt, Fabian Frederick, stable On Fri, Oct 16, 2020 at 2:09 PM Matteo Croce <mcroce@linux.microsoft.com> wrote: > > From: Matteo Croce <mcroce@microsoft.com> > > Limit the CPU number to num_possible_cpus(), because setting it > to a value lower than INT_MAX but higher than NR_CPUS produces the > following error on reboot and shutdown: > > BUG: unable to handle page fault for address: ffffffff90ab1bb0 > #PF: supervisor read access in kernel mode > #PF: error_code(0x0000) - not-present page > PGD 1c09067 P4D 1c09067 PUD 1c0a063 PMD 0 > Oops: 0000 [#1] SMP > CPU: 1 PID: 1 Comm: systemd-shutdow Not tainted 5.9.0-rc8-kvm #110 > Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.13.0-2.fc32 04/01/2014 > RIP: 0010:migrate_to_reboot_cpu+0xe/0x60 > Code: ea ea 00 48 89 fa 48 c7 c7 30 57 f1 81 e9 fa ef ff ff 66 2e 0f 1f 84 00 00 00 00 00 53 8b 1d d5 ea ea 00 e8 14 33 fe ff 89 da <48> 0f a3 15 ea fc bd 00 48 89 d0 73 29 89 c2 c1 e8 06 65 48 8b 3c > RSP: 0018:ffffc90000013e08 EFLAGS: 00010246 > RAX: ffff88801f0a0000 RBX: 0000000077359400 RCX: 0000000000000000 > RDX: 0000000077359400 RSI: 0000000000000002 RDI: ffffffff81c199e0 > RBP: ffffffff81c1e3c0 R08: ffff88801f41f000 R09: ffffffff81c1e348 > R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 > R13: 00007f32bedf8830 R14: 00000000fee1dead R15: 0000000000000000 > FS: 00007f32bedf8980(0000) GS:ffff88801f480000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: ffffffff90ab1bb0 CR3: 000000001d057000 CR4: 00000000000006a0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > Call Trace: > __do_sys_reboot.cold+0x34/0x5b > ? vfs_writev+0x92/0xc0 > ? do_writev+0x52/0xd0 > do_syscall_64+0x2d/0x40 > entry_SYSCALL_64_after_hwframe+0x44/0xa9 > RIP: 0033:0x7f32bfaaecd3 > Code: 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 89 fa be 69 19 12 28 bf ad de e1 fe b8 a9 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 05 c3 0f 1f 40 00 48 8b 15 89 81 0c 00 f7 d8 > RSP: 002b:00007fff6265fb58 EFLAGS: 00000202 ORIG_RAX: 00000000000000a9 > RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f32bfaaecd3 > RDX: 0000000001234567 RSI: 0000000028121969 RDI: 00000000fee1dead > RBP: 0000000000000000 R08: 0000000000008020 R09: 00007fff6265ef60 > R10: 00007f32bedf8830 R11: 0000000000000202 R12: 0000000000000000 > R13: 0000557bba2c51c0 R14: 0000000000000000 R15: 00007fff6265fbc8 > CR2: ffffffff90ab1bb0 > ---[ end trace b813e80157136563 ]--- > RIP: 0010:migrate_to_reboot_cpu+0xe/0x60 > Code: ea ea 00 48 89 fa 48 c7 c7 30 57 f1 81 e9 fa ef ff ff 66 2e 0f 1f 84 00 00 00 00 00 53 8b 1d d5 ea ea 00 e8 14 33 fe ff 89 da <48> 0f a3 15 ea fc bd 00 48 89 d0 73 29 89 c2 c1 e8 06 65 48 8b 3c > RSP: 0018:ffffc90000013e08 EFLAGS: 00010246 > RAX: ffff88801f0a0000 RBX: 0000000077359400 RCX: 0000000000000000 > RDX: 0000000077359400 RSI: 0000000000000002 RDI: ffffffff81c199e0 > RBP: ffffffff81c1e3c0 R08: ffff88801f41f000 R09: ffffffff81c1e348 > R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 > R13: 00007f32bedf8830 R14: 00000000fee1dead R15: 0000000000000000 > FS: 00007f32bedf8980(0000) GS:ffff88801f480000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: ffffffff90ab1bb0 CR3: 000000001d057000 CR4: 00000000000006a0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000009 > Kernel Offset: disabled > ---[ end Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000009 ]--- > > Fixes: 1b3a5d02ee07 ("reboot: move arch/x86 reboot= handling to generic kernel") > Signed-off-by: Matteo Croce <mcroce@microsoft.com> Reviewed-by: Pavel Tatashin <pasha.tatashin@soleen.com> ^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH 1/2] reboot: fix overflow parsing reboot cpu number 2020-10-16 18:09 ` [PATCH 1/2] reboot: fix overflow parsing reboot cpu number Matteo Croce 2020-10-16 19:25 ` Kees Cook 2020-10-16 19:45 ` Pavel Tatashin @ 2020-10-19 13:18 ` Petr Mladek 2 siblings, 0 replies; 10+ messages in thread From: Petr Mladek @ 2020-10-19 13:18 UTC (permalink / raw) To: Matteo Croce Cc: linux-kernel, Guenter Roeck, Arnd Bergmann, Mike Rapoport, Kees Cook, Pavel Tatashin, Robin Holt, Fabian Frederick, stable On Fri 2020-10-16 20:09:06, Matteo Croce wrote: > From: Matteo Croce <mcroce@microsoft.com> > > Limit the CPU number to num_possible_cpus(), because setting it > to a value lower than INT_MAX but higher than NR_CPUS produces the > following error on reboot and shutdown: > > Fixes: 1b3a5d02ee07 ("reboot: move arch/x86 reboot= handling to generic kernel") > Signed-off-by: Matteo Croce <mcroce@microsoft.com> Reviewed-by: Petr Mladek <pmladek@suse.com> Best Regards, Petr ^ permalink raw reply [flat|nested] 10+ messages in thread
* [PATCH 2/2] reboot: fix parsing of reboot cpu number 2020-10-16 18:09 [PATCH 0/2] fix parsing of reboot= cmdline Matteo Croce 2020-10-16 18:09 ` [PATCH 1/2] reboot: fix overflow parsing reboot cpu number Matteo Croce @ 2020-10-16 18:09 ` Matteo Croce 2020-10-16 19:26 ` Kees Cook ` (2 more replies) 1 sibling, 3 replies; 10+ messages in thread From: Matteo Croce @ 2020-10-16 18:09 UTC (permalink / raw) To: linux-kernel Cc: Guenter Roeck, Petr Mladek, Arnd Bergmann, Mike Rapoport, Kees Cook, Pavel Tatashin, Robin Holt, Fabian Frederick, stable From: Matteo Croce <mcroce@microsoft.com> The kernel cmdline reboot= argument allows to specify the CPU used for rebooting, with the syntax `s####` among the other flags, e.g. reboot=soft,s4 reboot=warm,s31,force In the early days the parsing was done with simple_strtoul(), later deprecated in favor of the safer kstrtoint() which handles overflow. But kstrtoint() returns -EINVAL if there are non-digit characters in a string, so if this flag is not the last given, it's silently ignored as well as the subsequent ones. To fix it, revert the usage of simple_strtoul(), which is no longer deprecated, and restore the old behaviour. While at it, merge two identical code blocks into one. Fixes: 616feab75397 ("kernel/reboot.c: convert simple_strtoul to kstrtoint") Signed-off-by: Matteo Croce <mcroce@microsoft.com> --- kernel/reboot.c | 30 ++++++++++++------------------ 1 file changed, 12 insertions(+), 18 deletions(-) diff --git a/kernel/reboot.c b/kernel/reboot.c index c4e7965c39b9..475f790bbd75 100644 --- a/kernel/reboot.c +++ b/kernel/reboot.c @@ -552,25 +552,19 @@ static int __init reboot_setup(char *str) case 's': { - int rc; - - if (isdigit(*(str+1))) { - rc = kstrtoint(str+1, 0, &reboot_cpu); - if (rc) - return rc; - if (reboot_cpu >= num_possible_cpus()) { - reboot_cpu = 0; - return -ERANGE; - } - } else if (str[1] == 'm' && str[2] == 'p' && - isdigit(*(str+3))) { - rc = kstrtoint(str+3, 0, &reboot_cpu); - if (rc) - return rc; - if (reboot_cpu >= num_possible_cpus()) { - reboot_cpu = 0; + int cpu; + + /* + * reboot_cpu is s[mp]#### with #### being the processor + * to be used for rebooting. Skip 's' or 'smp' prefix. + */ + str += str[1] == 'm' && str[2] == 'p' ? 3 : 1; + + if (isdigit(str[0])) { + cpu = simple_strtoul(str, NULL, 10); + if (cpu >= num_possible_cpus()) return -ERANGE; - } + reboot_cpu = cpu; } else *mode = REBOOT_SOFT; break; -- 2.26.2 ^ permalink raw reply related [flat|nested] 10+ messages in thread
* Re: [PATCH 2/2] reboot: fix parsing of reboot cpu number 2020-10-16 18:09 ` [PATCH 2/2] reboot: fix parsing of " Matteo Croce @ 2020-10-16 19:26 ` Kees Cook 2020-10-16 21:34 ` Matteo Croce 2020-10-16 19:46 ` Pavel Tatashin 2020-10-19 13:49 ` Petr Mladek 2 siblings, 1 reply; 10+ messages in thread From: Kees Cook @ 2020-10-16 19:26 UTC (permalink / raw) To: Matteo Croce Cc: linux-kernel, Guenter Roeck, Petr Mladek, Arnd Bergmann, Mike Rapoport, Pavel Tatashin, Robin Holt, Fabian Frederick, stable On Fri, Oct 16, 2020 at 08:09:07PM +0200, Matteo Croce wrote: > From: Matteo Croce <mcroce@microsoft.com> > > The kernel cmdline reboot= argument allows to specify the CPU used > for rebooting, with the syntax `s####` among the other flags, e.g. > > reboot=soft,s4 > reboot=warm,s31,force > > In the early days the parsing was done with simple_strtoul(), later > deprecated in favor of the safer kstrtoint() which handles overflow. > > But kstrtoint() returns -EINVAL if there are non-digit characters > in a string, so if this flag is not the last given, it's silently > ignored as well as the subsequent ones. > > To fix it, revert the usage of simple_strtoul(), which is no longer > deprecated, and restore the old behaviour. It is? Is there a reference, because this was never updated: https://www.kernel.org/doc/html/latest/process/deprecated.html#simple-strtol-simple-strtoll-simple-strtoul-simple-strtoull -- Kees Cook ^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH 2/2] reboot: fix parsing of reboot cpu number 2020-10-16 19:26 ` Kees Cook @ 2020-10-16 21:34 ` Matteo Croce 0 siblings, 0 replies; 10+ messages in thread From: Matteo Croce @ 2020-10-16 21:34 UTC (permalink / raw) To: Kees Cook, Petr Mladek Cc: linux-kernel, Guenter Roeck, Arnd Bergmann, Mike Rapoport, Pavel Tatashin, Robin Holt, Fabian Frederick, stable On Fri, Oct 16, 2020 at 9:26 PM Kees Cook <keescook@chromium.org> wrote: > > On Fri, Oct 16, 2020 at 08:09:07PM +0200, Matteo Croce wrote: > > From: Matteo Croce <mcroce@microsoft.com> > > > > The kernel cmdline reboot= argument allows to specify the CPU used > > for rebooting, with the syntax `s####` among the other flags, e.g. > > > > reboot=soft,s4 > > reboot=warm,s31,force > > > > In the early days the parsing was done with simple_strtoul(), later > > deprecated in favor of the safer kstrtoint() which handles overflow. > > > > But kstrtoint() returns -EINVAL if there are non-digit characters > > in a string, so if this flag is not the last given, it's silently > > ignored as well as the subsequent ones. > > > > To fix it, revert the usage of simple_strtoul(), which is no longer > > deprecated, and restore the old behaviour. > > It is? Is there a reference, because this was never updated: > https://www.kernel.org/doc/html/latest/process/deprecated.html#simple-strtol-simple-strtoll-simple-strtoul-simple-strtoull > > -- > Kees Cook Seems so, Petr Mladek replied to the previous patch: > I suggest to go back to simple_strtoul(). It is not longer obsolete. > It still exists because it is needed for exactly this purpose, > see the comment in include/linux/kernel.h The comment says: /* * Use kstrto<foo> instead. * * NOTE: simple_strto<foo> does not check for the range overflow and, * depending on the input, may give interesting results. * * Use these functions if and only if you cannot use kstrto<foo>, because * the conversion ends on the first non-digit character, which may be far * beyond the supported range. It might be useful to parse the strings like * 10x50 or 12:21 without altering original string or temporary buffer in use. * Keep in mind above caveat. */ https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/include/linux/kernel.h?h=v5.9#n452 Cheers, -- per aspera ad upstream ^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH 2/2] reboot: fix parsing of reboot cpu number 2020-10-16 18:09 ` [PATCH 2/2] reboot: fix parsing of " Matteo Croce 2020-10-16 19:26 ` Kees Cook @ 2020-10-16 19:46 ` Pavel Tatashin 2020-10-19 13:49 ` Petr Mladek 2 siblings, 0 replies; 10+ messages in thread From: Pavel Tatashin @ 2020-10-16 19:46 UTC (permalink / raw) To: Matteo Croce Cc: LKML, Guenter Roeck, Petr Mladek, Arnd Bergmann, Mike Rapoport, Kees Cook, Robin Holt, Fabian Frederick, stable On Fri, Oct 16, 2020 at 2:09 PM Matteo Croce <mcroce@linux.microsoft.com> wrote: > > From: Matteo Croce <mcroce@microsoft.com> > > The kernel cmdline reboot= argument allows to specify the CPU used > for rebooting, with the syntax `s####` among the other flags, e.g. > > reboot=soft,s4 > reboot=warm,s31,force > > In the early days the parsing was done with simple_strtoul(), later > deprecated in favor of the safer kstrtoint() which handles overflow. > > But kstrtoint() returns -EINVAL if there are non-digit characters > in a string, so if this flag is not the last given, it's silently > ignored as well as the subsequent ones. > > To fix it, revert the usage of simple_strtoul(), which is no longer > deprecated, and restore the old behaviour. > > While at it, merge two identical code blocks into one. > > Fixes: 616feab75397 ("kernel/reboot.c: convert simple_strtoul to kstrtoint") > Signed-off-by: Matteo Croce <mcroce@microsoft.com> Reviewed-by: Pavel Tatashin <pasha.tatashin@soleen.com> ^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH 2/2] reboot: fix parsing of reboot cpu number 2020-10-16 18:09 ` [PATCH 2/2] reboot: fix parsing of " Matteo Croce 2020-10-16 19:26 ` Kees Cook 2020-10-16 19:46 ` Pavel Tatashin @ 2020-10-19 13:49 ` Petr Mladek 2 siblings, 0 replies; 10+ messages in thread From: Petr Mladek @ 2020-10-19 13:49 UTC (permalink / raw) To: Matteo Croce Cc: linux-kernel, Guenter Roeck, Arnd Bergmann, Mike Rapoport, Kees Cook, Pavel Tatashin, Robin Holt, Fabian Frederick, stable On Fri 2020-10-16 20:09:07, Matteo Croce wrote: > From: Matteo Croce <mcroce@microsoft.com> > > The kernel cmdline reboot= argument allows to specify the CPU used > for rebooting, with the syntax `s####` among the other flags, e.g. > > reboot=soft,s4 > reboot=warm,s31,force > > In the early days the parsing was done with simple_strtoul(), later > deprecated in favor of the safer kstrtoint() which handles overflow. > > But kstrtoint() returns -EINVAL if there are non-digit characters > in a string, so if this flag is not the last given, it's silently > ignored as well as the subsequent ones. > > To fix it, revert the usage of simple_strtoul(), which is no longer > deprecated, and restore the old behaviour. > > While at it, merge two identical code blocks into one. > > Fixes: 616feab75397 ("kernel/reboot.c: convert simple_strtoul to kstrtoint") > Signed-off-by: Matteo Croce <mcroce@microsoft.com> > --- > diff --git a/kernel/reboot.c b/kernel/reboot.c > index c4e7965c39b9..475f790bbd75 100644 > --- a/kernel/reboot.c > +++ b/kernel/reboot.c > @@ -552,25 +552,19 @@ static int __init reboot_setup(char *str) > > case 's': > { > - int rc; > - > - if (isdigit(*(str+1))) { > - rc = kstrtoint(str+1, 0, &reboot_cpu); > - if (rc) > - return rc; > - if (reboot_cpu >= num_possible_cpus()) { > - reboot_cpu = 0; > - return -ERANGE; > - } > - } else if (str[1] == 'm' && str[2] == 'p' && > - isdigit(*(str+3))) { > - rc = kstrtoint(str+3, 0, &reboot_cpu); > - if (rc) > - return rc; > - if (reboot_cpu >= num_possible_cpus()) { > - reboot_cpu = 0; > + int cpu; > + > + /* > + * reboot_cpu is s[mp]#### with #### being the processor > + * to be used for rebooting. Skip 's' or 'smp' prefix. > + */ > + str += str[1] == 'm' && str[2] == 'p' ? 3 : 1; > + > + if (isdigit(str[0])) { > + cpu = simple_strtoul(str, NULL, 10); The original code did not force the base 10. And even the code before the commit 616feab75397 ("kernel/reboot.c: convert simple_strtoul to kstrtoint") did not force the base 10. I am not sure if people use it. But sometimes it might be easier to define the CPU number in hexa format. With using simple_strtoul(str, NULL, 0): Reviewed-by: Petr Mladek <pmladek@suse.com> Best Regards, Petr ^ permalink raw reply [flat|nested] 10+ messages in thread
end of thread, other threads:[~2020-10-19 13:49 UTC | newest] Thread overview: 10+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2020-10-16 18:09 [PATCH 0/2] fix parsing of reboot= cmdline Matteo Croce 2020-10-16 18:09 ` [PATCH 1/2] reboot: fix overflow parsing reboot cpu number Matteo Croce 2020-10-16 19:25 ` Kees Cook 2020-10-16 19:45 ` Pavel Tatashin 2020-10-19 13:18 ` Petr Mladek 2020-10-16 18:09 ` [PATCH 2/2] reboot: fix parsing of " Matteo Croce 2020-10-16 19:26 ` Kees Cook 2020-10-16 21:34 ` Matteo Croce 2020-10-16 19:46 ` Pavel Tatashin 2020-10-19 13:49 ` Petr Mladek
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