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Diffstat (limited to 'crypto/asymmetric_keys/verify_pefile.c')
-rw-r--r--crypto/asymmetric_keys/verify_pefile.c49
1 files changed, 33 insertions, 16 deletions
diff --git a/crypto/asymmetric_keys/verify_pefile.c b/crypto/asymmetric_keys/verify_pefile.c
index 79175e6ea0b2..2421f46184ce 100644
--- a/crypto/asymmetric_keys/verify_pefile.c
+++ b/crypto/asymmetric_keys/verify_pefile.c
@@ -128,6 +128,7 @@ static int pefile_strip_sig_wrapper(const void *pebuf,
{
struct win_certificate wrapper;
const u8 *pkcs7;
+ unsigned len;
if (ctx->sig_len < sizeof(wrapper)) {
pr_debug("Signature wrapper too short\n");
@@ -154,33 +155,49 @@ static int pefile_strip_sig_wrapper(const void *pebuf,
return -ENOTSUPP;
}
- /* Looks like actual pkcs signature length is in wrapper->length.
- * size obtained from data dir entries lists the total size of
- * certificate table which is also aligned to octawrod boundary.
- *
- * So set signature length field appropriately.
+ /* It looks like the pkcs signature length in wrapper->length and the
+ * size obtained from the data dir entries, which lists the total size
+ * of certificate table, are both aligned to an octaword boundary, so
+ * we may have to deal with some padding.
*/
ctx->sig_len = wrapper.length;
ctx->sig_offset += sizeof(wrapper);
ctx->sig_len -= sizeof(wrapper);
- if (ctx->sig_len == 0) {
+ if (ctx->sig_len < 4) {
pr_debug("Signature data missing\n");
return -EKEYREJECTED;
}
- /* What's left should a PKCS#7 cert */
+ /* What's left should be a PKCS#7 cert */
pkcs7 = pebuf + ctx->sig_offset;
- if (pkcs7[0] == (ASN1_CONS_BIT | ASN1_SEQ)) {
- if (pkcs7[1] == 0x82 &&
- pkcs7[2] == (((ctx->sig_len - 4) >> 8) & 0xff) &&
- pkcs7[3] == ((ctx->sig_len - 4) & 0xff))
- return 0;
- if (pkcs7[1] == 0x80)
- return 0;
- if (pkcs7[1] > 0x82)
- return -EMSGSIZE;
+ if (pkcs7[0] != (ASN1_CONS_BIT | ASN1_SEQ))
+ goto not_pkcs7;
+
+ switch (pkcs7[1]) {
+ case 0 ... 0x7f:
+ len = pkcs7[1] + 2;
+ goto check_len;
+ case ASN1_INDEFINITE_LENGTH:
+ return 0;
+ case 0x81:
+ len = pkcs7[2] + 3;
+ goto check_len;
+ case 0x82:
+ len = ((pkcs7[2] << 8) | pkcs7[3]) + 4;
+ goto check_len;
+ case 0x83 ... 0xff:
+ return -EMSGSIZE;
+ default:
+ goto not_pkcs7;
}
+check_len:
+ if (len <= ctx->sig_len) {
+ /* There may be padding */
+ ctx->sig_len = len;
+ return 0;
+ }
+not_pkcs7:
pr_debug("Signature data not PKCS#7\n");
return -ELIBBAD;
}