[gentoo-commits] proj/sandbox:master commit in: libsandbox/

[Mike Gilbert]

commit:     811054d8bb60728bb485c007f7961856c9666407
Author:     Mike Gilbert <floppym <AT> gentoo <DOT> org>
AuthorDate: Thu Feb  6 16:33:49 2025 +0000
Commit:     Mike Gilbert <floppym <AT> gentoo <DOT> org>
CommitDate: Sat Feb 15 01:42:41 2025 +0000
URL:        https://gitweb.gentoo.org/proj/sandbox.git/commit/?id=811054d8

Add overflow checking in malloc, cmalloc

Signed-off-by: Mike Gilbert <floppym <AT> gentoo.org>

 libsandbox/memory.c | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/libsandbox/memory.c b/libsandbox/memory.c
index 69aa972..a23e87a 100644
--- a/libsandbox/memory.c
+++ b/libsandbox/memory.c
@@ -49,9 +49,11 @@ static int sb_munmap(void *addr, size_t length)
 
 void *malloc(size_t size)
 {
-       size_t *ret;
-       size += MIN_ALIGN;
-       ret = mmap(0, size, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, 
-1, 0);
+       if (__builtin_add_overflow(size, MIN_ALIGN, &size)) {
+               errno = ENOMEM;
+               return NULL;
+       }
+       size_t *ret = mmap(0, size, PROT_READ|PROT_WRITE, 
MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
        if (ret == MAP_FAILED)
                return NULL;
        *ret = size;
@@ -70,9 +72,13 @@ void free(void *ptr)
 /* Hrm, implement a zalloc() ? */
 void *calloc(size_t nmemb, size_t size)
 {
-       void *ret = malloc(nmemb * size); /* dont care about overflow */
+       if (__builtin_mul_overflow(nmemb, size, &size)) {
+               errno = ENOMEM;
+               return NULL;
+       }
+       void *ret = malloc(size);
        if (ret)
-               memset(ret, 0, nmemb * size);
+               memset(ret, 0, size);
        return ret;
 }