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authorRich Felker <dalias@aerifal.cx>2014-01-02 17:03:34 -0500
committerRich Felker <dalias@aerifal.cx>2014-01-02 17:03:34 -0500
commit7a995fe706e519a4f55399776ef0df9596101f93 (patch)
tree72e03908db98617da9d06eadb8e1d83a0206772d
parent5c81b8fe453994a74afa7cd355dd707ee2d01a24 (diff)
downloadmusl-7a995fe706e519a4f55399776ef0df9596101f93.tar.gz
disable sbrk for all values of increment except 0
use of sbrk is never safe; it conflicts with malloc, and malloc may be used internally by the implementation basically anywhere. prior to this change, applications attempting to use sbrk to do their own heap management simply caused untrackable memory corruption; now, they will fail with ENOMEM allowing the errors to be fixed. sbrk(0) is still permitted as a way to get the current brk; some misguided applications use this as a measurement of their memory usage or for other related purposes, and such usage is harmless. eventually sbrk may be re-added if/when malloc is changed to avoid using the brk by using mmap for all allocations.
-rw-r--r--src/linux/sbrk.c6
1 files changed, 3 insertions, 3 deletions
diff --git a/src/linux/sbrk.c b/src/linux/sbrk.c
index 36437653..1e82d643 100644
--- a/src/linux/sbrk.c
+++ b/src/linux/sbrk.c
@@ -1,9 +1,9 @@
#include <stdint.h>
+#include <errno.h>
#include "syscall.h"
void *sbrk(intptr_t inc)
{
- unsigned long cur = syscall(SYS_brk, 0);
- if (inc && syscall(SYS_brk, cur+inc) != cur+inc) return (void *)-1;
- return (void *)cur;
+ if (inc) return (void *)__syscall_ret(-ENOMEM);
+ return (void *)__syscall(SYS_brk, 0);
}