* [PATCH] s390/debug: Replace kmalloc() + copy_from_user() with memdup_user_nul()
@ 2025-09-04 11:40 Thorsten Blum
2025-09-04 12:14 ` Niklas Schnelle
2025-09-08 11:50 ` Alexander Gordeev
0 siblings, 2 replies; 3+ messages in thread
From: Thorsten Blum @ 2025-09-04 11:40 UTC (permalink / raw)
To: Heiko Carstens, Vasily Gorbik, Alexander Gordeev,
Christian Borntraeger, Sven Schnelle, Halil Pasic,
Niklas Schnelle, Bill O'Donnell, Al Viro, Tigran Mkrtchyan,
Joel Granados
Cc: Thorsten Blum, Wei Liu, linux-s390, linux-kernel
Replace kmalloc() followed by copy_from_user() with memdup_user_nul() to
improve and simplify debug_get_user_string(). Remove the manual
NUL-termination.
No functional changes intended.
Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
---
arch/s390/kernel/debug.c | 12 +++---------
1 file changed, 3 insertions(+), 9 deletions(-)
diff --git a/arch/s390/kernel/debug.c b/arch/s390/kernel/debug.c
index c62100dc62c8..6a26f202441d 100644
--- a/arch/s390/kernel/debug.c
+++ b/arch/s390/kernel/debug.c
@@ -1416,18 +1416,12 @@ static inline char *debug_get_user_string(const char __user *user_buf,
{
char *buffer;
- buffer = kmalloc(user_len + 1, GFP_KERNEL);
- if (!buffer)
- return ERR_PTR(-ENOMEM);
- if (copy_from_user(buffer, user_buf, user_len) != 0) {
- kfree(buffer);
- return ERR_PTR(-EFAULT);
- }
+ buffer = memdup_user_nul(user_buf, user_len);
+ if (IS_ERR(buffer))
+ return buffer;
/* got the string, now strip linefeed. */
if (buffer[user_len - 1] == '\n')
buffer[user_len - 1] = 0;
- else
- buffer[user_len] = 0;
return buffer;
}
--
2.51.0
^ permalink raw reply related [flat|nested] 3+ messages in thread* Re: [PATCH] s390/debug: Replace kmalloc() + copy_from_user() with memdup_user_nul()
2025-09-04 11:40 [PATCH] s390/debug: Replace kmalloc() + copy_from_user() with memdup_user_nul() Thorsten Blum
@ 2025-09-04 12:14 ` Niklas Schnelle
2025-09-08 11:50 ` Alexander Gordeev
1 sibling, 0 replies; 3+ messages in thread
From: Niklas Schnelle @ 2025-09-04 12:14 UTC (permalink / raw)
To: Thorsten Blum, Heiko Carstens, Vasily Gorbik, Alexander Gordeev,
Christian Borntraeger, Sven Schnelle, Halil Pasic,
Bill O'Donnell, Al Viro, Tigran Mkrtchyan, Joel Granados
Cc: Wei Liu, linux-s390, linux-kernel
On Thu, 2025-09-04 at 13:40 +0200, Thorsten Blum wrote:
> Replace kmalloc() followed by copy_from_user() with memdup_user_nul() to
> improve and simplify debug_get_user_string(). Remove the manual
> NUL-termination.
>
> No functional changes intended.
>
> Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
> ---
> arch/s390/kernel/debug.c | 12 +++---------
> 1 file changed, 3 insertions(+), 9 deletions(-)
>
> diff --git a/arch/s390/kernel/debug.c b/arch/s390/kernel/debug.c
> index c62100dc62c8..6a26f202441d 100644
> --- a/arch/s390/kernel/debug.c
> +++ b/arch/s390/kernel/debug.c
> @@ -1416,18 +1416,12 @@ static inline char *debug_get_user_string(const char __user *user_buf,
> {
> char *buffer;
>
> - buffer = kmalloc(user_len + 1, GFP_KERNEL);
> - if (!buffer)
> - return ERR_PTR(-ENOMEM);
> - if (copy_from_user(buffer, user_buf, user_len) != 0) {
> - kfree(buffer);
> - return ERR_PTR(-EFAULT);
> - }
> + buffer = memdup_user_nul(user_buf, user_len);
> + if (IS_ERR(buffer))
> + return buffer;
> /* got the string, now strip linefeed. */
> if (buffer[user_len - 1] == '\n')
> buffer[user_len - 1] = 0;
> - else
> - buffer[user_len] = 0;
> return buffer;
> }
>
I like it, thanks!
Reviewed-by: Niklas Schnelle <schnelle@linux.ibm.com>
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH] s390/debug: Replace kmalloc() + copy_from_user() with memdup_user_nul()
2025-09-04 11:40 [PATCH] s390/debug: Replace kmalloc() + copy_from_user() with memdup_user_nul() Thorsten Blum
2025-09-04 12:14 ` Niklas Schnelle
@ 2025-09-08 11:50 ` Alexander Gordeev
1 sibling, 0 replies; 3+ messages in thread
From: Alexander Gordeev @ 2025-09-08 11:50 UTC (permalink / raw)
To: Thorsten Blum
Cc: Heiko Carstens, Vasily Gorbik, Christian Borntraeger,
Sven Schnelle, Halil Pasic, Niklas Schnelle, Bill O'Donnell,
Al Viro, Tigran Mkrtchyan, Joel Granados, Wei Liu, linux-s390,
linux-kernel
On Thu, Sep 04, 2025 at 01:40:29PM +0200, Thorsten Blum wrote:
> Replace kmalloc() followed by copy_from_user() with memdup_user_nul() to
> improve and simplify debug_get_user_string(). Remove the manual
> NUL-termination.
>
> No functional changes intended.
>
> Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
> ---
> arch/s390/kernel/debug.c | 12 +++---------
> 1 file changed, 3 insertions(+), 9 deletions(-)
Applied, thanks!
^ permalink raw reply [flat|nested] 3+ messages in thread
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2025-09-04 11:40 [PATCH] s390/debug: Replace kmalloc() + copy_from_user() with memdup_user_nul() Thorsten Blum
2025-09-04 12:14 ` Niklas Schnelle
2025-09-08 11:50 ` Alexander Gordeev
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