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509: fix printing uninitialized stack memory when OID is empty 

Callers of sprint_oid() do not check its return value before printing
the result.  In the case where the OID is zero-length, -EBADMSG was
being returned without anything being written to the buffer, resulting
in uninitialized stack memory being printed.  Fix this by writing
"(bad)" to the buffer in the cases where -EBADMSG is returned.

Fixes: 4f73175d03 ("X.509: Add utility functions to render OIDs as strings")
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: David Howells <dhowells@redhat.com>
This commit is contained in:
Eric Biggers 2017-12-08 15:13:28 +00:00 committed by David Howells
parent 47e0a208fb
commit 8dfd2f22d3
1 changed files with 6 additions and 2 deletions
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8
lib/oid_registry.c
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@ -116,7 +116,7 @@ int sprint_oid(const void *data, size_t datasize, char *buffer, size_t bufsize)
int count;
if (v >= end)
return -EBADMSG;
goto bad;
n = *v++;
ret = count = snprintf(buffer, bufsize, "%u.%u", n / 40, n % 40);
@ -134,7 +134,7 @@ int sprint_oid(const void *data, size_t datasize, char *buffer, size_t bufsize)
num = n & 0x7f;
do {
if (v >= end)
return -EBADMSG;
goto bad;
n = *v++;
num <<= 7;
num |= n & 0x7f;
@ -148,6 +148,10 @@ int sprint_oid(const void *data, size_t datasize, char *buffer, size_t bufsize)
}
return ret;
bad:
snprintf(buffer, bufsize, "(bad)");
return -EBADMSG;
}
EXPORT_SYMBOL_GPL(sprint_oid);