[PATCH v3 05/13] loader: Generalise is_addr_reserved to find overlapping address ranges.
Jinoh Kang
jinoh.kang.kr at gmail.com
Tue Jan 25 09:24:53 CST 2022
Rename is_addr_reserved to find_preload_reserved_area, with the
following changes:
- Accept second argument "size" which specifies the size of the address
range to test.
- Return the index of the matching entry, or -1 if none found.
Signed-off-by: Jinoh Kang <jinoh.kang.kr at gmail.com>
---
Notes:
v1 -> v2: handle overflows
loader/preloader.c | 19 ++++++++++++-------
1 file changed, 12 insertions(+), 7 deletions(-)
diff --git a/loader/preloader.c b/loader/preloader.c
index 54a8b8bac2f..fb22eff5f61 100644
--- a/loader/preloader.c
+++ b/loader/preloader.c
@@ -1436,17 +1436,22 @@ error:
}
/* check if address is in one of the reserved ranges */
-static int is_addr_reserved( const void *addr )
+static int find_preload_reserved_area( const void *addr, size_t size )
{
+ unsigned long start = (unsigned long)addr;
+ unsigned long end = (unsigned long)addr + size - 1;
int i;
+ if (!size)
+ return -1;
+
for (i = 0; preload_info[i].size; i++)
{
- if ((const char *)addr >= (const char *)preload_info[i].addr &&
- (const char *)addr < (const char *)preload_info[i].addr + preload_info[i].size)
- return 1;
+ if (end >= (unsigned long)preload_info[i].addr &&
+ start <= (unsigned long)preload_info[i].addr + preload_info[i].size - 1)
+ return i;
}
- return 0;
+ return -1;
}
/* remove a range from the preload list */
@@ -1469,7 +1474,7 @@ static int is_in_preload_range( const struct wld_auxv *av, int type )
{
while (av->a_type != AT_NULL)
{
- if (av->a_type == type) return is_addr_reserved( (const void *)av->a_un.a_val );
+ if (av->a_type == type) return find_preload_reserved_area( (const void *)av->a_un.a_val, 1 ) >= 0;
av++;
}
return 0;
@@ -1557,7 +1562,7 @@ void* wld_start( void **stack )
/* add an executable page at the top of the address space to defeat
* broken no-exec protections that play with the code selector limit */
- if (is_addr_reserved( (char *)0x80000000 - page_size ))
+ if (find_preload_reserved_area( (char *)0x80000000 - page_size, page_size ) >= 0)
wld_mprotect( (char *)0x80000000 - page_size, page_size, PROT_EXEC | PROT_READ );
/* load the main binary */
--
2.31.1
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