* [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
* [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 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 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 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 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 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 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
* 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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