* [PATCH v2 0/2] fix parsing of reboot= cmdline
@ 2020-10-27 13:35 Matteo Croce
2020-10-27 13:35 ` [PATCH v2 1/2] reboot: fix overflow parsing reboot cpu number Matteo Croce
` (2 more replies)
0 siblings, 3 replies; 8+ messages in thread
From: Matteo Croce @ 2020-10-27 13:35 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.
v1->v2:
As Petr suggested, don't force base 10 in simple_strtoul(),
so hex values are accepted as well.
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(-)
--
2.28.0
^ permalink raw reply [flat|nested] 8+ messages in thread
* [PATCH v2 1/2] reboot: fix overflow parsing reboot cpu number
2020-10-27 13:35 [PATCH v2 0/2] fix parsing of reboot= cmdline Matteo Croce
@ 2020-10-27 13:35 ` Matteo Croce
2020-10-27 13:42 ` Greg KH
2020-10-27 13:35 ` [PATCH v2 2/2] reboot: fix parsing of " Matteo Croce
2020-10-27 13:42 ` [PATCH v2 0/2] fix parsing of reboot= cmdline Greg KH
2 siblings, 1 reply; 8+ messages in thread
From: Matteo Croce @ 2020-10-27 13:35 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;
--
2.28.0
^ permalink raw reply related [flat|nested] 8+ messages in thread
* [PATCH v2 2/2] reboot: fix parsing of reboot cpu number
2020-10-27 13:35 [PATCH v2 0/2] fix parsing of reboot= cmdline Matteo Croce
2020-10-27 13:35 ` [PATCH v2 1/2] reboot: fix overflow parsing reboot cpu number Matteo Croce
@ 2020-10-27 13:35 ` Matteo Croce
2020-10-27 13:42 ` Greg KH
2020-10-30 14:30 ` Petr Mladek
2020-10-27 13:42 ` [PATCH v2 0/2] fix parsing of reboot= cmdline Greg KH
2 siblings, 2 replies; 8+ messages in thread
From: Matteo Croce @ 2020-10-27 13:35 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..a09c5937c0b6 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, 0);
+ if (cpu >= num_possible_cpus())
return -ERANGE;
- }
+ reboot_cpu = cpu;
} else
*mode = REBOOT_SOFT;
break;
--
2.28.0
^ permalink raw reply related [flat|nested] 8+ messages in thread
* Re: [PATCH v2 0/2] fix parsing of reboot= cmdline
2020-10-27 13:35 [PATCH v2 0/2] fix parsing of reboot= cmdline Matteo Croce
2020-10-27 13:35 ` [PATCH v2 1/2] reboot: fix overflow parsing reboot cpu number Matteo Croce
2020-10-27 13:35 ` [PATCH v2 2/2] reboot: fix parsing of " Matteo Croce
@ 2020-10-27 13:42 ` Greg KH
2 siblings, 0 replies; 8+ messages in thread
From: Greg KH @ 2020-10-27 13:42 UTC (permalink / raw)
To: Matteo Croce
Cc: linux-kernel, Guenter Roeck, Petr Mladek, Arnd Bergmann,
Mike Rapoport, Kees Cook, Pavel Tatashin, Robin Holt,
Fabian Frederick, stable
On Tue, Oct 27, 2020 at 02:35:43PM +0100, Matteo Croce wrote:
> 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.
>
> v1->v2:
> As Petr suggested, don't force base 10 in simple_strtoul(),
> so hex values are accepted as well.
>
> 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(-)
>
> --
> 2.28.0
>
<formletter>
This is not the correct way to submit patches for inclusion in the
stable kernel tree. Please read:
https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
for how to do this properly.
</formletter>
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH v2 2/2] reboot: fix parsing of reboot cpu number
2020-10-27 13:35 ` [PATCH v2 2/2] reboot: fix parsing of " Matteo Croce
@ 2020-10-27 13:42 ` Greg KH
2020-10-30 14:30 ` Petr Mladek
1 sibling, 0 replies; 8+ messages in thread
From: Greg KH @ 2020-10-27 13:42 UTC (permalink / raw)
To: Matteo Croce
Cc: linux-kernel, Guenter Roeck, Petr Mladek, Arnd Bergmann,
Mike Rapoport, Kees Cook, Pavel Tatashin, Robin Holt,
Fabian Frederick, stable
On Tue, Oct 27, 2020 at 02:35:45PM +0100, 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>
> ---
> kernel/reboot.c | 30 ++++++++++++------------------
> 1 file changed, 12 insertions(+), 18 deletions(-)
>
<formletter>
This is not the correct way to submit patches for inclusion in the
stable kernel tree. Please read:
https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
for how to do this properly.
</formletter>
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH v2 1/2] reboot: fix overflow parsing reboot cpu number
2020-10-27 13:35 ` [PATCH v2 1/2] reboot: fix overflow parsing reboot cpu number Matteo Croce
@ 2020-10-27 13:42 ` Greg KH
2020-10-30 14:13 ` Petr Mladek
0 siblings, 1 reply; 8+ messages in thread
From: Greg KH @ 2020-10-27 13:42 UTC (permalink / raw)
To: Matteo Croce
Cc: linux-kernel, Guenter Roeck, Petr Mladek, Arnd Bergmann,
Mike Rapoport, Kees Cook, Pavel Tatashin, Robin Holt,
Fabian Frederick, stable
On Tue, Oct 27, 2020 at 02:35:44PM +0100, 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>
> ---
> kernel/reboot.c | 8 ++++++++
> 1 file changed, 8 insertions(+)
>
<formletter>
This is not the correct way to submit patches for inclusion in the
stable kernel tree. Please read:
https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
for how to do this properly.
</formletter>
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH v2 1/2] reboot: fix overflow parsing reboot cpu number
2020-10-27 13:42 ` Greg KH
@ 2020-10-30 14:13 ` Petr Mladek
0 siblings, 0 replies; 8+ messages in thread
From: Petr Mladek @ 2020-10-30 14:13 UTC (permalink / raw)
To: Greg KH
Cc: Matteo Croce, linux-kernel, Guenter Roeck, Arnd Bergmann,
Mike Rapoport, Kees Cook, Pavel Tatashin, Robin Holt,
Fabian Frederick, stable
On Tue 2020-10-27 14:42:43, Greg KH wrote:
> On Tue, Oct 27, 2020 at 02:35:44PM +0100, 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>
> <formletter>
>
> This is not the correct way to submit patches for inclusion in the
> stable kernel tree. Please read:
> https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
> for how to do this properly.
>
> </formletter>
The best way is to add the following line before Signed-off-by line:
Cc: stable@vger.kernel.org
Best Regards,
Petr
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH v2 2/2] reboot: fix parsing of reboot cpu number
2020-10-27 13:35 ` [PATCH v2 2/2] reboot: fix parsing of " Matteo Croce
2020-10-27 13:42 ` Greg KH
@ 2020-10-30 14:30 ` Petr Mladek
1 sibling, 0 replies; 8+ messages in thread
From: Petr Mladek @ 2020-10-30 14:30 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 Tue 2020-10-27 14:35:45, 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.
> --- 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, 0);
> + if (cpu >= num_possible_cpus())
> return -ERANGE;
> - }
> + reboot_cpu = cpu;
The original value stays when the new one is out of range. It is
small functional change that should get mentioned in the commit
message or better fixed separately.
Hmm, I suggest to split this into 3 patches and switch the order:
+ 1st patch should simply revert the commit 616feab75397
("kernel/reboot.c: convert simple_strtoul to kstrtoint").
+ 2nd patch should merge the two branches without any
functional change.
+ 3rd patch should add the check for num_possible_cpus()
and update the value only when it is valid.
I am sorry that I did not suggested this when reviewed v1.
I have missed this functional change at that time.
Best Regards,
Petr
^ permalink raw reply [flat|nested] 8+ messages in thread
end of thread, other threads:[~2020-10-30 14:30 UTC | newest]
Thread overview: 8+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2020-10-27 13:35 [PATCH v2 0/2] fix parsing of reboot= cmdline Matteo Croce
2020-10-27 13:35 ` [PATCH v2 1/2] reboot: fix overflow parsing reboot cpu number Matteo Croce
2020-10-27 13:42 ` Greg KH
2020-10-30 14:13 ` Petr Mladek
2020-10-27 13:35 ` [PATCH v2 2/2] reboot: fix parsing of " Matteo Croce
2020-10-27 13:42 ` Greg KH
2020-10-30 14:30 ` Petr Mladek
2020-10-27 13:42 ` [PATCH v2 0/2] fix parsing of reboot= cmdline Greg KH
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox