[PATCH 1/2] X.509: Fix double free in x509_cert_parse()

David Howells
2016-11-24T08:51:14Z

From: Andrey Ryabinin <aryabinin@virtuozzo.com>

We shouldn't free cert->pub->key in x509_cert_parse() because
x509_free_certificate() also does this:
BUG: Double free or freeing an invalid pointer
...
Call Trace:
[<ffffffff81896c20>] dump_stack+0x63/0x83
[<ffffffff81356571>] kasan_object_err+0x21/0x70
[<ffffffff81356ed9>] kasan_report_double_free+0x49/0x60
[<ffffffff813561ad>] kasan_slab_free+0x9d/0xc0
[<ffffffff81350b7a>] kfree+0x8a/0x1a0
[<ffffffff81844fbf>] public_key_free+0x1f/0x30
[<ffffffff818455d4>] x509_free_certificate+0x24/0x90
[<ffffffff818460bc>] x509_cert_parse+0x2bc/0x300
[<ffffffff81846cae>] x509_key_preparse+0x3e/0x330
[<ffffffff818444cf>] asymmetric_key_preparse+0x6f/0x100
[<ffffffff8178bec0>] key_create_or_update+0x260/0x5f0
[<ffffffff8178e6d9>] SyS_add_key+0x199/0x2a0
[<ffffffff821d823b>] entry_SYSCALL_64_fastpath+0x1e/0xad
Object at ffff880110bd1900, in cache kmalloc-512 size: 512
....
Freed:
PID = 2579
[<ffffffff8104283b>] save_stack_trace+0x1b/0x20
[<ffffffff813558f6>] save_stack+0x46/0xd0
[<ffffffff81356183>] kasan_slab_free+0x73/0xc0
[<ffffffff81350b7a>] kfree+0x8a/0x1a0
[<ffffffff818460a3>] x509_cert_parse+0x2a3/0x300
[<ffffffff81846cae>] x509_key_preparse+0x3e/0x330
[<ffffffff818444cf>] asymmetric_key_preparse+0x6f/0x100
[<ffffffff8178bec0>] key_create_or_update+0x260/0x5f0
[<ffffffff8178e6d9>] SyS_add_key+0x199/0x2a0
[<ffffffff821d823b>] entry_SYSCALL_64_fastpath+0x1e/0xad

Fixes: db6c43bd2132 ("crypto: KEYS: convert public key and digsig asym to the akcipher api")
Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: David Howells <dhowells@redhat.com>
---

crypto/asymmetric_keys/x509_cert_parser.c | 1 -
1 file changed, 1 deletion(-)

diff --git a/crypto/asymmetric_keys/x509_cert_parser.c b/crypto/asymmetric_keys/x509_cert_parser.c
index 865f46ea724f..c80765b211cf 100644
--- a/crypto/asymmetric_keys/x509_cert_parser.c
+++ b/crypto/asymmetric_keys/x509_cert_parser.c
@@ -133,7 +133,6 @@ struct x509_certificate *x509_cert_parse(const void *data, size_t datalen)
return cert;

error_decode:
- kfree(cert->pub->key);
kfree(ctx);
error_no_ctx:
x509_free_certificate(cert);