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Merge branch '2363-alloca-docs' into 'master'

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galloca: Clarify alloca() sizes must always be controlled by the program

Closes #2363

See merge request GNOME/glib!2014
This commit is contained in:
Simon McVittie 2021-03-25 17:27:23 +00:00
commit 760ba5c4f1
1 changed files with 11 additions and 0 deletions
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glib/galloca.h
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@ -81,6 +81,11 @@ G_END_DECLS
* way as out of stack space situations from infinite function recursion, i.e.
* with a segmentation fault.
*
* - Allowing @size to be specified by an untrusted party would allow for them
* to trigger a segmentation fault by specifying a large size, leading to a
* denial of service vulnerability. @size must always be entirely under the
* control of the program.
*
* - Special care has to be taken when mixing alloca() with GNU C variable sized arrays.
* Stack space allocated with alloca() in the same scope as a variable sized array
* will be freed together with the variable sized array upon exit of that scope, and
@ -96,6 +101,12 @@ G_END_DECLS
*
* Wraps g_alloca() in a more typesafe manner.
*
* As mentioned in the documentation for g_alloca(), @n_structs must always be
* entirely under the control of the program, or you may introduce a denial of
* service vulnerability. In addition, the multiplication of @struct_type by
* @n_structs is not checked, so an overflow may lead to a remote code execution
* vulnerability.
*
* Returns: Pointer to stack space for @n_structs chunks of type @struct_type
*/
#define g_newa(struct_type, n_structs) ((struct_type*) g_alloca (sizeof (struct_type) * (gsize) (n_structs)))