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arm: Validate memory before access 

Prevent SIGSEGV due to accessing addresses now mapped to current process

Signed-off-by: Vyacheslav Barinov <v.barinov@samsung.com>
This commit is contained in:
Vyacheslav Barinov 2015-04-15 14:08:06 +03:00 committed by Arun Sharma
parent 16bf4e5e49
commit 7701522688
1 changed files with 55 additions and 0 deletions
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55
src/arm/Ginit.c
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@ -72,6 +72,56 @@ get_dyn_info_list_addr (unw_addr_space_t as, unw_word_t *dyn_info_list_addr,
return 0;
}
#define PAGE_SIZE 4096
#define PAGE_START(a) ((a) & ~(PAGE_SIZE-1))
/* Cache of already validated addresses */
#define NLGA 4
static unw_word_t last_good_addr[NLGA];
static int lga_victim;
static int
validate_mem (unw_word_t addr)
{
int i, victim;
size_t len;
if (PAGE_START(addr + sizeof (unw_word_t) - 1) == PAGE_START(addr))
len = PAGE_SIZE;
else
len = PAGE_SIZE * 2;
addr = PAGE_START(addr);
if (addr == 0)
return -1;
for (i = 0; i < NLGA; i++)
{
if (last_good_addr[i] && (addr == last_good_addr[i]))
return 0;
}
if (msync ((void *) addr, len, MS_ASYNC) == -1)
return -1;
victim = lga_victim;
for (i = 0; i < NLGA; i++) {
if (!last_good_addr[victim]) {
last_good_addr[victim++] = addr;
return 0;
}
victim = (victim + 1) % NLGA;
}
/* All slots full. Evict the victim. */
last_good_addr[victim] = addr;
victim = (victim + 1) % NLGA;
lga_victim = victim;
return 0;
}
static int
access_mem (unw_addr_space_t as, unw_word_t addr, unw_word_t *val, int write,
void *arg)
@ -83,6 +133,11 @@ access_mem (unw_addr_space_t as, unw_word_t addr, unw_word_t *val, int write,
}
else
{
/* validate address */
const struct cursor *c = (const struct cursor *) arg;
if (c && validate_mem(addr))
return -1;
*val = *(unw_word_t *) addr;
Debug (16, "mem[%x] -> %x\n", addr, *val);
}