* [PATCH] LoongArch: Avoid in-place string operation on FDT content
@ 2025-07-05 12:57 Yao Zi
2025-07-05 14:05 ` Jiaxun Yang
0 siblings, 1 reply; 3+ messages in thread
From: Yao Zi @ 2025-07-05 12:57 UTC (permalink / raw)
To: Huacai Chen, WANG Xuerui, Miaoqian Lin, Yao Zi, Hongliang Wang,
Binbin Zhou, Jiaxun Yang
Cc: loongarch, linux-kernel, Mingcong Bai, Kexy Biscuit
In init_cpu_fullname, a constant pointer to model property is retrieved.
It's later modified by the strsep function, which is illegal and
corrupts kernel's FDT copy. This is shown by dmesg,
OF: fdt: not creating '/sys/firmware/fdt': CRC check failed
Create a mutable copy of the model property and do in-place operations
on it instead. loongson_sysconf.cpuname lives across the kernel
lifetime, thus manually releasing isn't necessary.
Also move of_node_put() for the root node after the usage of its
property, since of_node_put() decreases the reference counter thus usage
after the call is unsafe.
Fixes: 44a01f1f726a ("LoongArch: Parsing CPU-related information from DTS")
Signed-off-by: Yao Zi <ziyao@disroot.org>
---
arch/loongarch/kernel/env.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)
diff --git a/arch/loongarch/kernel/env.c b/arch/loongarch/kernel/env.c
index 27144de5c5fe..fba141472ab9 100644
--- a/arch/loongarch/kernel/env.c
+++ b/arch/loongarch/kernel/env.c
@@ -40,15 +40,18 @@ void __init init_environ(void)
static int __init init_cpu_fullname(void)
{
struct device_node *root;
+ const char *model;
int cpu, ret;
- char *model;
+ char *tmp;
/* Parsing cpuname from DTS model property */
root = of_find_node_by_path("/");
- ret = of_property_read_string(root, "model", (const char **)&model);
+ ret = of_property_read_string(root, "model", &model);
+ if (ret == 0) {
+ tmp = kstrdup(model, GFP_KERNEL);
+ loongson_sysconf.cpuname = strsep(&tmp, " ");
+ }
of_node_put(root);
- if (ret == 0)
- loongson_sysconf.cpuname = strsep(&model, " ");
if (loongson_sysconf.cpuname && !strncmp(loongson_sysconf.cpuname, "Loongson", 8)) {
for (cpu = 0; cpu < NR_CPUS; cpu++)
--
2.49.0
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH] LoongArch: Avoid in-place string operation on FDT content
2025-07-05 12:57 [PATCH] LoongArch: Avoid in-place string operation on FDT content Yao Zi
@ 2025-07-05 14:05 ` Jiaxun Yang
2025-07-08 12:37 ` Huacai Chen
0 siblings, 1 reply; 3+ messages in thread
From: Jiaxun Yang @ 2025-07-05 14:05 UTC (permalink / raw)
To: Yao Zi, Huacai Chen, Xuerui Wang, Miaoqian Lin, Hongliang Wang,
Binbin Zhou
Cc: loongarch, linux-kernel, Mingcong Bai, Kexy Biscuit
在2025年7月5日周六 下午1:57，Yao Zi写道：
> In init_cpu_fullname, a constant pointer to model property is retrieved.
> It's later modified by the strsep function, which is illegal and
> corrupts kernel's FDT copy. This is shown by dmesg,
>
> OF: fdt: not creating '/sys/firmware/fdt': CRC check failed
>
> Create a mutable copy of the model property and do in-place operations
> on it instead. loongson_sysconf.cpuname lives across the kernel
> lifetime, thus manually releasing isn't necessary.
>
> Also move of_node_put() for the root node after the usage of its
> property, since of_node_put() decreases the reference counter thus usage
> after the call is unsafe.
>
> Fixes: 44a01f1f726a ("LoongArch: Parsing CPU-related information from DTS")
Reviewed-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
> Signed-off-by: Yao Zi <ziyao@disroot.org>
> ---
> arch/loongarch/kernel/env.c | 11 +++++++----
> 1 file changed, 7 insertions(+), 4 deletions(-)
>
> diff --git a/arch/loongarch/kernel/env.c b/arch/loongarch/kernel/env.c
> index 27144de5c5fe..fba141472ab9 100644
> --- a/arch/loongarch/kernel/env.c
> +++ b/arch/loongarch/kernel/env.c
> @@ -40,15 +40,18 @@ void __init init_environ(void)
> static int __init init_cpu_fullname(void)
> {
> struct device_node *root;
> + const char *model;
> int cpu, ret;
> - char *model;
> + char *tmp;
>
> /* Parsing cpuname from DTS model property */
> root = of_find_node_by_path("/");
> - ret = of_property_read_string(root, "model", (const char **)&model);
> + ret = of_property_read_string(root, "model", &model);
> + if (ret == 0) {
> + tmp = kstrdup(model, GFP_KERNEL);
> + loongson_sysconf.cpuname = strsep(&tmp, " ");
> + }
> of_node_put(root);
> - if (ret == 0)
> - loongson_sysconf.cpuname = strsep(&model, " ");
>
> if (loongson_sysconf.cpuname && !strncmp(loongson_sysconf.cpuname,
> "Loongson", 8)) {
> for (cpu = 0; cpu < NR_CPUS; cpu++)
> --
> 2.49.0
--
- Jiaxun
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH] LoongArch: Avoid in-place string operation on FDT content
2025-07-05 14:05 ` Jiaxun Yang
@ 2025-07-08 12:37 ` Huacai Chen
0 siblings, 0 replies; 3+ messages in thread
From: Huacai Chen @ 2025-07-08 12:37 UTC (permalink / raw)
To: Jiaxun Yang
Cc: Yao Zi, Xuerui Wang, Miaoqian Lin, Hongliang Wang, Binbin Zhou,
loongarch, linux-kernel, Mingcong Bai, Kexy Biscuit
Applied, thanks.
Huacai
On Sat, Jul 5, 2025 at 10:06 PM Jiaxun Yang <jiaxun.yang@flygoat.com> wrote:
>
>
>
> 在2025年7月5日周六 下午1:57，Yao Zi写道：
> > In init_cpu_fullname, a constant pointer to model property is retrieved.
> > It's later modified by the strsep function, which is illegal and
> > corrupts kernel's FDT copy. This is shown by dmesg,
> >
> > OF: fdt: not creating '/sys/firmware/fdt': CRC check failed
> >
> > Create a mutable copy of the model property and do in-place operations
> > on it instead. loongson_sysconf.cpuname lives across the kernel
> > lifetime, thus manually releasing isn't necessary.
> >
> > Also move of_node_put() for the root node after the usage of its
> > property, since of_node_put() decreases the reference counter thus usage
> > after the call is unsafe.
> >
> > Fixes: 44a01f1f726a ("LoongArch: Parsing CPU-related information from DTS")
>
> Reviewed-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
>
> > Signed-off-by: Yao Zi <ziyao@disroot.org>
> > ---
> > arch/loongarch/kernel/env.c | 11 +++++++----
> > 1 file changed, 7 insertions(+), 4 deletions(-)
> >
> > diff --git a/arch/loongarch/kernel/env.c b/arch/loongarch/kernel/env.c
> > index 27144de5c5fe..fba141472ab9 100644
> > --- a/arch/loongarch/kernel/env.c
> > +++ b/arch/loongarch/kernel/env.c
> > @@ -40,15 +40,18 @@ void __init init_environ(void)
> > static int __init init_cpu_fullname(void)
> > {
> > struct device_node *root;
> > + const char *model;
> > int cpu, ret;
> > - char *model;
> > + char *tmp;
> >
> > /* Parsing cpuname from DTS model property */
> > root = of_find_node_by_path("/");
> > - ret = of_property_read_string(root, "model", (const char **)&model);
> > + ret = of_property_read_string(root, "model", &model);
> > + if (ret == 0) {
> > + tmp = kstrdup(model, GFP_KERNEL);
> > + loongson_sysconf.cpuname = strsep(&tmp, " ");
> > + }
> > of_node_put(root);
> > - if (ret == 0)
> > - loongson_sysconf.cpuname = strsep(&model, " ");
> >
> > if (loongson_sysconf.cpuname && !strncmp(loongson_sysconf.cpuname,
> > "Loongson", 8)) {
> > for (cpu = 0; cpu < NR_CPUS; cpu++)
> > --
> > 2.49.0
>
> --
> - Jiaxun
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2025-07-08 12:38 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
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2025-07-05 12:57 [PATCH] LoongArch: Avoid in-place string operation on FDT content Yao Zi
2025-07-05 14:05 ` Jiaxun Yang
2025-07-08 12:37 ` Huacai Chen
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