5.10-stable review patch. If anyone has any objections, please let me know.
------------------
From: Edward Adam Davis <eadavis@xxxxxx>
commit 1997b3cb4217b09e49659b634c94da47f0340409 upstream.
The dns_resolver_preparse() function has a check on the size of the
payload for the basic header of the binary-style payload, but is missing
a check for the size of the V1 server-list payload header after
determining that's what we've been given.
Fix this by getting rid of the the pointer to the basic header and just
assuming that we have a V1 server-list payload and moving the V1 server
list pointer inside the if-statement. Dealing with other types and
versions can be left for when such have been defined.
This can be tested by doing the following with KASAN enabled:
echo -n -e '\x0\x0\x1\x2' | keyctl padd dns_resolver foo @p
and produces an oops like the following:
BUG: KASAN: slab-out-of-bounds in dns_resolver_preparse+0xc9f/0xd60 net/dns_resolver/dns_key.c:127
Read of size 1 at addr ffff888028894084 by task syz-executor265/5069
...
Call Trace:
dns_resolver_preparse+0xc9f/0xd60 net/dns_resolver/dns_key.c:127
__key_create_or_update+0x453/0xdf0 security/keys/key.c:842
key_create_or_update+0x42/0x50 security/keys/key.c:1007
__do_sys_add_key+0x29c/0x450 security/keys/keyctl.c:134
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0x40/0x110 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x62/0x6a
This patch was originally by Edward Adam Davis, but was modified by
Linus.
Fixes: b946001d3bb1 ("keys, dns: Allow key types (eg. DNS) to be reclaimed immediately on expiry")
Reported-and-tested-by: syzbot+94bbb75204a05da3d89f@xxxxxxxxxxxxxxxxxxxxxxxxx
Link: https://lore.kernel.org/r/0000000000009b39bc060c73e209@xxxxxxxxxx/
Suggested-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Edward Adam Davis <eadavis@xxxxxx>
Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
Tested-by: David Howells <dhowells@xxxxxxxxxx>
Cc: Edward Adam Davis <eadavis@xxxxxx>
Cc: Jarkko Sakkinen <jarkko@xxxxxxxxxx>
Cc: Jeffrey E Altman <jaltman@xxxxxxxxxxxx>
Cc: Wang Lei <wang840925@xxxxxxxxx>
Cc: Jeff Layton <jlayton@xxxxxxxxxx>
Cc: Steve French <sfrench@xxxxxxxxxx>
Cc: Marc Dionne <marc.dionne@xxxxxxxxxxxx>
Cc: "David S. Miller" <davem@xxxxxxxxxxxxx>
Cc: Eric Dumazet <edumazet@xxxxxxxxxx>
Cc: Jakub Kicinski <kuba@xxxxxxxxxx>
Cc: Paolo Abeni <pabeni@xxxxxxxxxx>
Reviewed-by: Simon Horman <horms@xxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Jeffrey E Altman <jaltman@xxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/dns_resolver/dns_key.c | 19 +++++++++----------
1 file changed, 9 insertions(+), 10 deletions(-)
--- a/net/dns_resolver/dns_key.c
+++ b/net/dns_resolver/dns_key.c
@@ -91,8 +91,6 @@ const struct cred *dns_resolver_cache;
static int
dns_resolver_preparse(struct key_preparsed_payload *prep)
{
- const struct dns_server_list_v1_header *v1;
- const struct dns_payload_header *bin;
struct user_key_payload *upayload;
unsigned long derrno;
int ret;
@@ -103,27 +101,28 @@ dns_resolver_preparse(struct key_prepars
return -EINVAL;
if (data[0] == 0) {
+ const struct dns_server_list_v1_header *v1;
+
/* It may be a server list. */
- if (datalen <= sizeof(*bin))
+ if (datalen <= sizeof(*v1))
return -EINVAL;
- bin = (const struct dns_payload_header *)data;
- kenter("[%u,%u],%u", bin->content, bin->version, datalen);
- if (bin->content != DNS_PAYLOAD_IS_SERVER_LIST) {
+ v1 = (const struct dns_server_list_v1_header *)data;
+ kenter("[%u,%u],%u", v1->hdr.content, v1->hdr.version, datalen);
+ if (v1->hdr.content != DNS_PAYLOAD_IS_SERVER_LIST) {
pr_warn_ratelimited(
"dns_resolver: Unsupported content type (%u)\n",
- bin->content);
+ v1->hdr.content);
return -EINVAL;
}
- if (bin->version != 1) {
+ if (v1->hdr.version != 1) {
pr_warn_ratelimited(
"dns_resolver: Unsupported server list version (%u)\n",
- bin->version);
+ v1->hdr.version);
return -EINVAL;
}
- v1 = (const struct dns_server_list_v1_header *)bin;
if ((v1->status != DNS_LOOKUP_GOOD &&
v1->status != DNS_LOOKUP_GOOD_WITH_BAD)) {
if (prep->expiry == TIME64_MAX)
