* [PATCH v3] setenv.c: Get rid of alloca.
@ 2023-06-29 15:15 Joe Simmons-Talbott
2023-06-30 13:07 ` Adhemerval Zanella Netto
0 siblings, 1 reply; 2+ messages in thread
From: Joe Simmons-Talbott @ 2023-06-29 15:15 UTC (permalink / raw)
To: libc-alpha; +Cc: Joe Simmons-Talbott
Use malloc rather than alloca to avoid potential stack overflow.
---
Changes to v2:
* Remove left-over include of scratch_buffer.h which is no longer
needed.
stdlib/setenv.c | 40 ++++++----------------------------------
1 file changed, 6 insertions(+), 34 deletions(-)
diff --git a/stdlib/setenv.c b/stdlib/setenv.c
index ba5257d3bf..cc71287fcc 100644
--- a/stdlib/setenv.c
+++ b/stdlib/setenv.c
@@ -182,18 +182,11 @@ __add_to_environ (const char *name, const char *value, const char *combined,
{
const size_t varlen = namelen + 1 + vallen;
#ifdef USE_TSEARCH
- char *new_value;
- int use_alloca = __libc_use_alloca (varlen);
- if (__builtin_expect (use_alloca, 1))
- new_value = (char *) alloca (varlen);
- else
+ char *new_value = malloc (varlen);
+ if (new_value == NULL)
{
- new_value = malloc (varlen);
- if (new_value == NULL)
- {
- UNLOCK;
- return -1;
- }
+ UNLOCK;
+ return -1;
}
# ifdef _LIBC
__mempcpy (__mempcpy (__mempcpy (new_value, name, namelen), "=", 1),
@@ -209,35 +202,14 @@ __add_to_environ (const char *name, const char *value, const char *combined,
#endif
{
#ifdef USE_TSEARCH
- if (__glibc_unlikely (! use_alloca))
- np = new_value;
- else
+ np = new_value;
#endif
- {
- np = malloc (varlen);
- if (__glibc_unlikely (np == NULL))
- {
- UNLOCK;
- return -1;
- }
-
-#ifdef USE_TSEARCH
- memcpy (np, new_value, varlen);
-#else
- memcpy (np, name, namelen);
- np[namelen] = '=';
- memcpy (&np[namelen + 1], value, vallen);
-#endif
- }
/* And remember the value. */
STORE_VALUE (np);
}
#ifdef USE_TSEARCH
else
- {
- if (__glibc_unlikely (! use_alloca))
- free (new_value);
- }
+ free (new_value);
#endif
}
--
2.39.2
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [PATCH v3] setenv.c: Get rid of alloca.
2023-06-29 15:15 [PATCH v3] setenv.c: Get rid of alloca Joe Simmons-Talbott
@ 2023-06-30 13:07 ` Adhemerval Zanella Netto
0 siblings, 0 replies; 2+ messages in thread
From: Adhemerval Zanella Netto @ 2023-06-30 13:07 UTC (permalink / raw)
To: Joe Simmons-Talbott, libc-alpha
On 29/06/23 12:15, Joe Simmons-Talbott via Libc-alpha wrote:
> Use malloc rather than alloca to avoid potential stack overflow.
LGTM, thanks.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
> ---
> Changes to v2:
> * Remove left-over include of scratch_buffer.h which is no longer
> needed.
>
> stdlib/setenv.c | 40 ++++++----------------------------------
> 1 file changed, 6 insertions(+), 34 deletions(-)
>
> diff --git a/stdlib/setenv.c b/stdlib/setenv.c
> index ba5257d3bf..cc71287fcc 100644
> --- a/stdlib/setenv.c
> +++ b/stdlib/setenv.c
> @@ -182,18 +182,11 @@ __add_to_environ (const char *name, const char *value, const char *combined,
> {
> const size_t varlen = namelen + 1 + vallen;
> #ifdef USE_TSEARCH
> - char *new_value;
> - int use_alloca = __libc_use_alloca (varlen);
> - if (__builtin_expect (use_alloca, 1))
> - new_value = (char *) alloca (varlen);
> - else
> + char *new_value = malloc (varlen);
> + if (new_value == NULL)
> {
> - new_value = malloc (varlen);
> - if (new_value == NULL)
> - {
> - UNLOCK;
> - return -1;
> - }
> + UNLOCK;
> + return -1;
> }
> # ifdef _LIBC
> __mempcpy (__mempcpy (__mempcpy (new_value, name, namelen), "=", 1),
> @@ -209,35 +202,14 @@ __add_to_environ (const char *name, const char *value, const char *combined,
> #endif
> {
> #ifdef USE_TSEARCH
> - if (__glibc_unlikely (! use_alloca))
> - np = new_value;
> - else
> + np = new_value;
> #endif
> - {
> - np = malloc (varlen);
> - if (__glibc_unlikely (np == NULL))
> - {
> - UNLOCK;
> - return -1;
> - }
> -
> -#ifdef USE_TSEARCH
> - memcpy (np, new_value, varlen);
> -#else
> - memcpy (np, name, namelen);
> - np[namelen] = '=';
> - memcpy (&np[namelen + 1], value, vallen);
> -#endif
> - }
> /* And remember the value. */
> STORE_VALUE (np);
> }
> #ifdef USE_TSEARCH
> else
> - {
> - if (__glibc_unlikely (! use_alloca))
> - free (new_value);
> - }
> + free (new_value);
> #endif
> }
>
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2023-06-30 13:07 ` Adhemerval Zanella Netto
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