* [PATCH v2] sched/isolation: avoid reading past string in isolcpus parser
@ 2026-03-09 22:02 Joseph Salisbury
2026-03-09 22:09 ` Steven Rostedt
0 siblings, 1 reply; 2+ messages in thread
From: Joseph Salisbury @ 2026-03-09 22:02 UTC (permalink / raw)
To: Ingo Molnar, Peter Zijlstra, Juri Lelli, Vincent Guittot
Cc: Dietmar Eggemann, Steven Rostedt, Ben Segall, Mel Gorman,
Valentin Schneider, linux-kernel
The function housekeeping_isolcpus_setup() advanced the parser pointer
unconditionally after unknown flags.
For an argument like 'isolcpus=unknownflag', with no trailing
comma, this can move the pointer past the terminating NUL, and
the next loop test reads out of bounds.
Reproducer:
isolcpus=unknownflag
Advance only when the parser is not already at the terminating NUL,
preserving existing parsing semantics while avoiding the invalid read.
Fixes: 3662daf02350 ("sched/isolation: Allow "isolcpus=" to skip unknown sub-parameters")
Cc: stable@vger.kernel.org
Cc: Steven Rostedt <rostedt@goodmis.org>
Assisted-by: Codex:GPT-5
Signed-off-by: Joseph Salisbury <joseph.salisbury@oracle.com>
---
v2:
- Advance past any non-NUL separator instead of checking specifically
for ','.
kernel/sched/isolation.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/kernel/sched/isolation.c b/kernel/sched/isolation.c
index ef152d401fe2..402a1e335277 100644
--- a/kernel/sched/isolation.c
+++ b/kernel/sched/isolation.c
@@ -355,7 +355,8 @@ static int __init housekeeping_isolcpus_setup(char *str)
}
pr_info("isolcpus: Skipped unknown flag %.*s\n", len, par);
- str++;
+ if (*str)
+ str++;
}
/* Default behaviour for isolcpus without flags */
--
2.47.3
^ permalink raw reply [flat|nested] 2+ messages in thread* Re: [PATCH v2] sched/isolation: avoid reading past string in isolcpus parser
2026-03-09 22:02 [PATCH v2] sched/isolation: avoid reading past string in isolcpus parser Joseph Salisbury
@ 2026-03-09 22:09 ` Steven Rostedt
0 siblings, 0 replies; 2+ messages in thread
From: Steven Rostedt @ 2026-03-09 22:09 UTC (permalink / raw)
To: Joseph Salisbury
Cc: Ingo Molnar, Peter Zijlstra, Juri Lelli, Vincent Guittot,
Dietmar Eggemann, Ben Segall, Mel Gorman, Valentin Schneider,
linux-kernel
On Mon, 9 Mar 2026 18:02:16 -0400
Joseph Salisbury <joseph.salisbury@oracle.com> wrote:
> The function housekeeping_isolcpus_setup() advanced the parser pointer
> unconditionally after unknown flags.
>
> For an argument like 'isolcpus=unknownflag', with no trailing
> comma, this can move the pointer past the terminating NUL, and
> the next loop test reads out of bounds.
>
> Reproducer:
> isolcpus=unknownflag
>
> Advance only when the parser is not already at the terminating NUL,
> preserving existing parsing semantics while avoiding the invalid read.
>
> Fixes: 3662daf02350 ("sched/isolation: Allow "isolcpus=" to skip unknown sub-parameters")
> Cc: stable@vger.kernel.org
> Cc: Steven Rostedt <rostedt@goodmis.org>
> Assisted-by: Codex:GPT-5
> Signed-off-by: Joseph Salisbury <joseph.salisbury@oracle.com>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
-- Steve
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