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record: Fix OOB access in ProcRecordUnregisterClients 

If a client sends a RecordUnregisterClients request with an nClients
field larger than INT_MAX / 4, an integer overflow leads to an
out of boundary access in RecordSanityCheckClientSpecifiers.

An example line with libXtst would be:
XRecordUnregisterClients(dpy, rc, clients, 0x40000001);

Reviewed-by: Adam Jackson <ajax@redhat.com>
This commit is contained in:
Tobias Stoeckmann 2017-03-19 17:55:07 +01:00 committed by Adam Jackson
parent 1ad2306823
commit 40c12a76c2
1 changed files with 2 additions and 1 deletions
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3
record/record.c
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@ -1910,7 +1910,8 @@ ProcRecordUnregisterClients(ClientPtr client)
int i;
REQUEST_AT_LEAST_SIZE(xRecordUnregisterClientsReq);
if ((client->req_len << 2) - SIZEOF(xRecordUnregisterClientsReq) !=
if (INT_MAX / 4 < stuff->nClients ||
(client->req_len << 2) - SIZEOF(xRecordUnregisterClientsReq) !=
4 * stuff->nClients)
return BadLength;
VERIFY_CONTEXT(pContext, stuff->context, client);