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libsel4muslcsys: Return error if 0 len requested 

mmap is expected to return an error if a length of 0 is ever requested.

The caller is likely doing something wrong if a 0 length is requested
and it leads for hard to find bugs if we just return the current address
of the end of available memory.

Signed-off-by: Kent McLeod <1759184+kent-mcleod@users.noreply.github.com>
This commit is contained in:
Kent McLeod 2025-03-05 11:19:20 +11:00
parent d28e409727
commit 06527c27c7
1 changed files with 8 additions and 0 deletions
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8
libsel4muslcsys/src/sys_morecore.c
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@ -63,6 +63,10 @@ long sys_brk(va_list ap)
here to support that. We make a bunch of assumptions in the process */
long sys_mmap_impl(void *addr, size_t length, int prot, int flags, int fd, off_t offset)
{
if (length == 0) {
// It is an error to request a length 0 in most mmap specs.
return -EINVAL;
}
if (flags & MAP_ANONYMOUS) {
/* Check that we don't try and allocate more than exists */
if (length > morecore_top - morecore_base) {
@ -228,6 +232,10 @@ static long sys_mmap_impl_dynamic(void *addr, size_t length, int prot, int flags
long sys_mmap_impl(void *addr, size_t length, int prot, int flags, int fd, off_t offset)
{
if (length == 0) {
// It is an error to request a length 0 in most mmap specs.
return -EINVAL;
}
if (morecore_area != NULL) {
return sys_mmap_impl_static(addr, length, prot, flags, fd, offset);
} else if (muslc_this_vspace != NULL) {