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authorRich Felker <dalias@aerifal.cx>2017-09-06 22:09:28 -0400
committerRich Felker <dalias@aerifal.cx>2017-09-06 22:15:14 -0400
commitda438ee1fc516c41ba1790cef7be551a9e244397 (patch)
tree6f0778c3e0dbca45b4bd5c19c672db995b6e3ad1
parent8c4be3e2209d2a1d3874b8bc2b474668fcbbbac6 (diff)
downloadmusl-da438ee1fc516c41ba1790cef7be551a9e244397.tar.gz
work around incorrect EPERM from mmap syscall
under some conditions, the mmap syscall wrongly fails with EPERM instead of ENOMEM when memory is exhausted; this is probably the result of the kernel trying to fit the allocation somewhere that crosses into the kernel range or below mmap_min_addr. in any case it's a conformance bug, so work around it. for now, only handle the case of anonymous mappings with no requested address; in other cases EPERM may be a legitimate error. this indirectly fixes the possibility of malloc failing with the wrong errno value.
-rw-r--r--src/mman/mmap.c9
1 files changed, 7 insertions, 2 deletions
diff --git a/src/mman/mmap.c b/src/mman/mmap.c
index 19caadbd..15924033 100644
--- a/src/mman/mmap.c
+++ b/src/mman/mmap.c
@@ -14,6 +14,7 @@ weak_alias(dummy, __vm_wait);
void *__mmap(void *start, size_t len, int prot, int flags, int fd, off_t off)
{
+ long ret;
if (off & OFF_MASK) {
errno = EINVAL;
return MAP_FAILED;
@@ -26,10 +27,14 @@ void *__mmap(void *start, size_t len, int prot, int flags, int fd, off_t off)
__vm_wait();
}
#ifdef SYS_mmap2
- return (void *)syscall(SYS_mmap2, start, len, prot, flags, fd, off/UNIT);
+ ret = __syscall(SYS_mmap2, start, len, prot, flags, fd, off/UNIT);
#else
- return (void *)syscall(SYS_mmap, start, len, prot, flags, fd, off);
+ ret = __syscall(SYS_mmap, start, len, prot, flags, fd, off);
#endif
+ /* Fixup incorrect EPERM from kernel. */
+ if (ret == -EPERM && !start && (flags&MAP_ANON) && !(flags&MAP_FIXED))
+ ret = -ENOMEM;
+ return (void *)__syscall_ret(ret);
}
weak_alias(__mmap, mmap);