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bus-message: avoid wrap-around when using length read from message 

We would read (-1), and then add 1 to it, call message_peek_body(..., 0, ...),
and when trying to make use of the data.

The fuzzer test case is just for one site, but they all look similar.

v2: fix two UINT8_MAX/UINT32_MAX mismatches founds by LGTM
This commit is contained in:
Zbigniew Jędrzejewski-Szmek 2018-08-23 14:48:40 +02:00
parent d831fb6f2b
commit 902000c198
2 changed files with 24 additions and 0 deletions
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24
src/libsystemd/sd-bus/bus-message.c
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@ -3389,6 +3389,10 @@ _public_ int sd_bus_message_read_basic(sd_bus_message *m, char type, void *p) {
return r;
l = BUS_MESSAGE_BSWAP32(m, *(uint32_t*) q);
if (l == UINT32_MAX)
/* avoid overflow right below */
return -EBADMSG;
r = message_peek_body(m, &rindex, 1, l+1, &q);
if (r < 0)
return r;
@ -3411,6 +3415,10 @@ _public_ int sd_bus_message_read_basic(sd_bus_message *m, char type, void *p) {
return r;
l = *(uint8_t*) q;
if (l == UINT8_MAX)
/* avoid overflow right below */
return -EBADMSG;
r = message_peek_body(m, &rindex, 1, l+1, &q);
if (r < 0)
return r;
@ -3676,6 +3684,10 @@ static int bus_message_enter_variant(
return r;
l = *(uint8_t*) q;
if (l == UINT8_MAX)
/* avoid overflow right below */
return -EBADMSG;
r = message_peek_body(m, &rindex, 1, l+1, &q);
if (r < 0)
return r;
@ -4244,6 +4256,10 @@ _public_ int sd_bus_message_peek_type(sd_bus_message *m, char *type, const char
return r;
l = *(uint8_t*) q;
if (l == UINT8_MAX)
/* avoid overflow right below */
return -EBADMSG;
r = message_peek_body(m, &rindex, 1, l+1, &q);
if (r < 0)
return r;
@ -4826,6 +4842,10 @@ static int message_peek_field_string(
if (r < 0)
return r;
if (l == UINT32_MAX)
/* avoid overflow right below */
return -EBADMSG;
r = message_peek_fields(m, ri, 1, l+1, &q);
if (r < 0)
return r;
@ -4877,6 +4897,10 @@ static int message_peek_field_signature(
return r;
l = *(uint8_t*) q;
if (l == UINT8_MAX)
/* avoid overflow right below */
return -EBADMSG;
r = message_peek_fields(m, ri, 1, l+1, &q);
if (r < 0)
return r;

BIN
test/fuzz/fuzz-bus-message/crash-603dfd98252375ac7dbced53c2ec312671939a36 Normal file
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