[PATCH 1/3] PKCS#7: Fix panic when referring to the empty AKID when DEBUG defined
From: David Howells
Date: Sun Jul 17 2016 - 19:10:54 EST
From: Lans Zhang <jia.zhang@xxxxxxxxxxxxx>
This fix resolves the following kernel panic if an empty or missing
AuthorityKeyIdentifier is encountered and DEBUG is defined in
pkcs7_verify.c.
[ 459.041989] PKEY: <==public_key_verify_signature() = 0
[ 459.041993] PKCS7: Verified signature 1
[ 459.041995] PKCS7: ==> pkcs7_verify_sig_chain()
[ 459.041999] PKCS7: verify Sample DB Certificate for SCP: 01
[ 459.042002] PKCS7: - issuer Sample KEK Certificate for SCP
[ 459.042014] BUG: unable to handle kernel NULL pointer dereference at (null)
[ 459.042135] IP: [<ffffffff813e7b4c>] pkcs7_verify+0x72c/0x7f0
[ 459.042217] PGD 739e6067 PUD 77719067 PMD 0
[ 459.042286] Oops: 0000 [#1] PREEMPT SMP
[ 459.042328] Modules linked in:
[ 459.042368] CPU: 0 PID: 474 Comm: kexec Not tainted 4.7.0-rc7-WR8.0.0.0_standard+ #18
[ 459.042462] Hardware name: To be filled by O.E.M. To be filled by O.E.M./Aptio CRB, BIOS 5.6.5 10/09/2014
[ 459.042586] task: ffff880073a50000 ti: ffff8800738e8000 task.ti: ffff8800738e8000
[ 459.042675] RIP: 0010:[<ffffffff813e7b4c>] [<ffffffff813e7b4c>] pkcs7_verify+0x72c/0x7f0
[ 459.042784] RSP: 0018:ffff8800738ebd58 EFLAGS: 00010246
[ 459.042845] RAX: 0000000000000000 RBX: ffff880076b7da80 RCX: 0000000000000006
[ 459.042929] RDX: 0000000000000001 RSI: ffffffff81c85001 RDI: ffffffff81ca00a9
[ 459.043014] RBP: ffff8800738ebd98 R08: 0000000000000400 R09: ffff8800788a304c
[ 459.043098] R10: 0000000000000000 R11: 00000000000060ca R12: ffff8800769a2bc0
[ 459.043182] R13: ffff880077358300 R14: 0000000000000000 R15: ffff8800769a2dc0
[ 459.043268] FS: 00007f24cc741700(0000) GS:ffff880074e00000(0000) knlGS:0000000000000000
[ 459.043365] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 459.043431] CR2: 0000000000000000 CR3: 0000000073a36000 CR4: 00000000001006f0
[ 459.043514] Stack:
[ 459.043530] 0000000000000000 ffffffbf00000020 31ffffff813e68b0 0000000000000002
[ 459.043644] ffff8800769a2bc0 0000000000000000 00000000007197b8 0000000000000002
[ 459.043756] ffff8800738ebdd8 ffffffff81153fb1 0000000000000000 0000000000000000
[ 459.043869] Call Trace:
[ 459.043898] [<ffffffff81153fb1>] verify_pkcs7_signature+0x61/0x140
[ 459.043974] [<ffffffff813e7f0b>] verify_pefile_signature+0x2cb/0x830
[ 459.044052] [<ffffffff813e8470>] ? verify_pefile_signature+0x830/0x830
[ 459.044134] [<ffffffff81048e25>] bzImage64_verify_sig+0x15/0x20
[ 459.046332] [<ffffffff81046e09>] arch_kexec_kernel_verify_sig+0x29/0x40
[ 459.048552] [<ffffffff810f10e4>] SyS_kexec_file_load+0x1f4/0x6c0
[ 459.050768] [<ffffffff81050e36>] ? __do_page_fault+0x1b6/0x550
[ 459.052996] [<ffffffff8199241f>] entry_SYSCALL_64_fastpath+0x17/0x93
[ 459.055242] Code: e8 0a d6 ff ff 85 c0 0f 88 7a fb ff ff 4d 39 fd 4d 89 7d 08 74 45 4d 89 fd e9 14 fe ff ff 4d 8b 76 08 31 c0 48 c7 c7 a9 00 ca 81 <41> 0f b7 36 49 8d 56 02 e8 d0 91 d6 ff 4d 8b 3c 24 4d 85 ff 0f
[ 459.060535] RIP [<ffffffff813e7b4c>] pkcs7_verify+0x72c/0x7f0
[ 459.063040] RSP <ffff8800738ebd58>
[ 459.065456] CR2: 0000000000000000
[ 459.075998] ---[ end trace c15f0e897cda28dc ]---
Signed-off-by: Lans Zhang <jia.zhang@xxxxxxxxxxxxx>
Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
Cc: Dave Young <dyoung@xxxxxxxxxx>
Cc: Baoquan He <bhe@xxxxxxxxxx>
Cc: Vivek Goyal <vgoyal@xxxxxxxxxx>
cc: linux-crypto@xxxxxxxxxxxxxxx
cc: kexec@xxxxxxxxxxxxxxxxxxx
---
crypto/asymmetric_keys/pkcs7_verify.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/crypto/asymmetric_keys/pkcs7_verify.c b/crypto/asymmetric_keys/pkcs7_verify.c
index 44b746e9df1b..2ffd69769466 100644
--- a/crypto/asymmetric_keys/pkcs7_verify.c
+++ b/crypto/asymmetric_keys/pkcs7_verify.c
@@ -227,7 +227,7 @@ static int pkcs7_verify_sig_chain(struct pkcs7_message *pkcs7,
if (asymmetric_key_id_same(p->id, auth))
goto found_issuer_check_skid;
}
- } else {
+ } else if (sig->auth_ids[1]) {
auth = sig->auth_ids[1];
pr_debug("- want %*phN\n", auth->len, auth->data);
for (p = pkcs7->certs; p; p = p->next) {