Home Home > GIT Browse
summaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorAndrey Ryabinin <ryabinin.a.a@gmail.com>2014-07-26 21:26:58 +0400
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-08-14 09:24:15 +0800
commit15229fa9d4588b2d0e91ee81954c3a4f3c30dcb8 (patch)
tree11e012742d91ed65835ae549ebc4f8416c4f6e45
parent4176df017abbe847f0c09e5b839feb40e04b25ba (diff)
net: sendmsg: fix NULL pointer dereference
[ Upstream commit 40eea803c6b2cfaab092f053248cbeab3f368412 ] Sasha's report: > While fuzzing with trinity inside a KVM tools guest running the latest -next > kernel with the KASAN patchset, I've stumbled on the following spew: > > [ 4448.949424] ================================================================== > [ 4448.951737] AddressSanitizer: user-memory-access on address 0 > [ 4448.952988] Read of size 2 by thread T19638: > [ 4448.954510] CPU: 28 PID: 19638 Comm: trinity-c76 Not tainted 3.16.0-rc4-next-20140711-sasha-00046-g07d3099-dirty #813 > [ 4448.956823] ffff88046d86ca40 0000000000000000 ffff880082f37e78 ffff880082f37a40 > [ 4448.958233] ffffffffb6e47068 ffff880082f37a68 ffff880082f37a58 ffffffffb242708d > [ 4448.959552] 0000000000000000 ffff880082f37a88 ffffffffb24255b1 0000000000000000 > [ 4448.961266] Call Trace: > [ 4448.963158] dump_stack (lib/dump_stack.c:52) > [ 4448.964244] kasan_report_user_access (mm/kasan/report.c:184) > [ 4448.965507] __asan_load2 (mm/kasan/kasan.c:352) > [ 4448.966482] ? netlink_sendmsg (net/netlink/af_netlink.c:2339) > [ 4448.967541] netlink_sendmsg (net/netlink/af_netlink.c:2339) > [ 4448.968537] ? get_parent_ip (kernel/sched/core.c:2555) > [ 4448.970103] sock_sendmsg (net/socket.c:654) > [ 4448.971584] ? might_fault (mm/memory.c:3741) > [ 4448.972526] ? might_fault (./arch/x86/include/asm/current.h:14 mm/memory.c:3740) > [ 4448.973596] ? verify_iovec (net/core/iovec.c:64) > [ 4448.974522] ___sys_sendmsg (net/socket.c:2096) > [ 4448.975797] ? put_lock_stats.isra.13 (./arch/x86/include/asm/preempt.h:98 kernel/locking/lockdep.c:254) > [ 4448.977030] ? lock_release_holdtime (kernel/locking/lockdep.c:273) > [ 4448.978197] ? lock_release_non_nested (kernel/locking/lockdep.c:3434 (discriminator 1)) > [ 4448.979346] ? check_chain_key (kernel/locking/lockdep.c:2188) > [ 4448.980535] __sys_sendmmsg (net/socket.c:2181) > [ 4448.981592] ? trace_hardirqs_on_caller (kernel/locking/lockdep.c:2600) > [ 4448.982773] ? trace_hardirqs_on (kernel/locking/lockdep.c:2607) > [ 4448.984458] ? syscall_trace_enter (arch/x86/kernel/ptrace.c:1500 (discriminator 2)) > [ 4448.985621] ? trace_hardirqs_on_caller (kernel/locking/lockdep.c:2600) > [ 4448.986754] SyS_sendmmsg (net/socket.c:2201) > [ 4448.987708] tracesys (arch/x86/kernel/entry_64.S:542) > [ 4448.988929] ================================================================== This reports means that we've come to netlink_sendmsg() with msg->msg_name == NULL and msg->msg_namelen > 0. After this report there was no usual "Unable to handle kernel NULL pointer dereference" and this gave me a clue that address 0 is mapped and contains valid socket address structure in it. This bug was introduced in f3d3342602f8bcbf37d7c46641cb9bca7618eb1c (net: rework recvmsg handler msg_name and msg_namelen logic). Commit message states that: "Set msg->msg_name = NULL if user specified a NULL in msg_name but had a non-null msg_namelen in verify_iovec/verify_compat_iovec. This doesn't affect sendto as it would bail out earlier while trying to copy-in the address." But in fact this affects sendto when address 0 is mapped and contains socket address structure in it. In such case copy-in address will succeed, verify_iovec() function will successfully exit with msg->msg_namelen > 0 and msg->msg_name == NULL. This patch fixes it by setting msg_namelen to 0 if msg_name == NULL. Cc: Hannes Frederic Sowa <hannes@stressinduktion.org> Cc: Eric Dumazet <edumazet@google.com> Cc: <stable@vger.kernel.org> Reported-by: Sasha Levin <sasha.levin@oracle.com> Signed-off-by: Andrey Ryabinin <a.ryabinin@samsung.com> Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--net/compat.c9
-rw-r--r--net/core/iovec.c6
2 files changed, 8 insertions, 7 deletions
diff --git a/net/compat.c b/net/compat.c
index f50161fb812e..cbc1a2a26587 100644
--- a/net/compat.c
+++ b/net/compat.c
@@ -85,7 +85,7 @@ int verify_compat_iovec(struct msghdr *kern_msg, struct iovec *kern_iov,
{
int tot_len;
- if (kern_msg->msg_namelen) {
+ if (kern_msg->msg_name && kern_msg->msg_namelen) {
if (mode == VERIFY_READ) {
int err = move_addr_to_kernel(kern_msg->msg_name,
kern_msg->msg_namelen,
@@ -93,10 +93,11 @@ int verify_compat_iovec(struct msghdr *kern_msg, struct iovec *kern_iov,
if (err < 0)
return err;
}
- if (kern_msg->msg_name)
- kern_msg->msg_name = kern_address;
- } else
+ kern_msg->msg_name = kern_address;
+ } else {
kern_msg->msg_name = NULL;
+ kern_msg->msg_namelen = 0;
+ }
tot_len = iov_from_user_compat_to_kern(kern_iov,
(struct compat_iovec __user *)kern_msg->msg_iov,
diff --git a/net/core/iovec.c b/net/core/iovec.c
index 9a31515fb8e3..2145b7150beb 100644
--- a/net/core/iovec.c
+++ b/net/core/iovec.c
@@ -39,7 +39,7 @@ int verify_iovec(struct msghdr *m, struct iovec *iov, struct sockaddr_storage *a
{
int size, ct, err;
- if (m->msg_namelen) {
+ if (m->msg_name && m->msg_namelen) {
if (mode == VERIFY_READ) {
void __user *namep;
namep = (void __user __force *) m->msg_name;
@@ -48,10 +48,10 @@ int verify_iovec(struct msghdr *m, struct iovec *iov, struct sockaddr_storage *a
if (err < 0)
return err;
}
- if (m->msg_name)
- m->msg_name = address;
+ m->msg_name = address;
} else {
m->msg_name = NULL;
+ m->msg_namelen = 0;
}
size = m->msg_iovlen * sizeof(struct iovec);