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Message-ID: <20250905032544.231962-1-wangliang74@huawei.com>
Date: Fri, 5 Sep 2025 11:25:44 +0800
From: Wang Liang <wangliang74@...wei.com>
To: <rostedt@...dmis.org>, <mhiramat@...nel.org>,
<mathieu.desnoyers@...icios.com>, <tglozar@...hat.com>
CC: <yuehaibing@...wei.com>, <zhangchangzhong@...wei.com>,
<wangliang74@...wei.com>, <linux-trace-kernel@...r.kernel.org>,
<linux-kernel@...r.kernel.org>
Subject: [PATCH -next] tracing/osnoise: fix null-ptr-deref in bitmap_parselist
A crash was observed with the following output:
BUG: kernel NULL pointer dereference, address: 0000000000000010
Oops: Oops: 0000 [#1] SMP NOPTI
CPU: 2 UID: 0 PID: 92 Comm: osnoise_cpus Not tainted 6.17.0-rc4-00201-gd69eb204c255 #138 PREEMPT(voluntary)
RIP: 0010:bitmap_parselist+0x53/0x3e0
Call Trace:
<TASK>
osnoise_cpus_write+0x7a/0x190
vfs_write+0xf8/0x410
? do_sys_openat2+0x88/0xd0
ksys_write+0x60/0xd0
do_syscall_64+0xa4/0x260
entry_SYSCALL_64_after_hwframe+0x77/0x7f
</TASK>
This issue can be reproduced by below code:
fd=open("/sys/kernel/debug/tracing/osnoise/cpus", O_WRONLY);
write(fd, "0-2", 0);
When user pass 'count=0' to osnoise_cpus_write(), kmalloc() will return
ZERO_SIZE_PTR (16) and cpulist_parse() treat it as a normal value, which
trigger the null pointer dereference. Add check for the parameter 'count'.
Fixes: 17f89102fe23 ("tracing/osnoise: Allow arbitrarily long CPU string")
Signed-off-by: Wang Liang <wangliang74@...wei.com>
---
kernel/trace/trace_osnoise.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/kernel/trace/trace_osnoise.c b/kernel/trace/trace_osnoise.c
index fd259da0aa64..edf5178d0317 100644
--- a/kernel/trace/trace_osnoise.c
+++ b/kernel/trace/trace_osnoise.c
@@ -2322,6 +2322,9 @@ osnoise_cpus_write(struct file *filp, const char __user *ubuf, size_t count,
int running, err;
char *buf __free(kfree) = NULL;
+ if (count < 1)
+ return -EINVAL;
+
buf = kmalloc(count, GFP_KERNEL);
if (!buf)
return -ENOMEM;
--
2.33.0
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