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m25p80: avoid out of bounds accesses 

s->cur_addr can be made to point outside s->storage, either by
writing a value >= 128 to s->ear (because s->ear * MAX_3BYTES_SIZE
is a signed integer and sign-extends into the 64-bit cur_addr),
or just by writing an address beyond the size of the flash being
emulated.  Avoid the sign extension to make the code cleaner, and
on top of that mask s->cur_addr to s->size.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Message-id: 1467138270-32481-4-git-send-email-clg@kaod.org
Reviewed by: Marcin Krzeminski <marcin.krzeminski@nokia.com>
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
This commit is contained in:
Paolo Bonzini 2016-07-04 13:06:37 +01:00 committed by Peter Maydell
parent cace7b801d
commit b68cb06093
1 changed files with 7 additions and 9 deletions
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16
hw/block/m25p80.c
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@ -587,18 +587,16 @@ static inline int get_addr_length(Flash *s)
static void complete_collecting_data(Flash *s)
{
int i;
int i, n;
s->cur_addr = 0;
for (i = 0; i < get_addr_length(s); ++i) {
n = get_addr_length(s);
s->cur_addr = (n == 3 ? s->ear : 0);
for (i = 0; i < n; ++i) {
s->cur_addr <<= 8;
s->cur_addr |= s->data[i];
}
if (get_addr_length(s) == 3) {
s->cur_addr += s->ear * MAX_3BYTES_SIZE;
}
s->cur_addr &= s->size - 1;
s->state = STATE_IDLE;
@ -1100,14 +1098,14 @@ static uint32_t m25p80_transfer8(SSISlave *ss, uint32_t tx)
DB_PRINT_L(1, "page program cur_addr=%#" PRIx64 " data=%" PRIx8 "\n",
s->cur_addr, (uint8_t)tx);
flash_write8(s, s->cur_addr, (uint8_t)tx);
s->cur_addr++;
s->cur_addr = (s->cur_addr + 1) & (s->size - 1);
break;
case STATE_READ:
r = s->storage[s->cur_addr];
DB_PRINT_L(1, "READ 0x%" PRIx64 "=%" PRIx8 "\n", s->cur_addr,
(uint8_t)r);
s->cur_addr = (s->cur_addr + 1) % s->size;
s->cur_addr = (s->cur_addr + 1) & (s->size - 1);
break;
case STATE_COLLECTING_DATA: