diff mbox series

[net] net: fix possible NULL deref in sock_reserve_memory

Message ID 20211103234911.4073969-1-eric.dumazet@gmail.com (mailing list archive)
State Accepted
Commit d00c8ee31729248ba40b4ab25cd3b3b580c6f87c
Delegated to: Netdev Maintainers
Headers show
Series [net] net: fix possible NULL deref in sock_reserve_memory | expand

Checks

Context Check Description
netdev/tree_selection success Clearly marked for net
netdev/fixes_present success Fixes tag present in non-next series
netdev/subject_prefix success Link
netdev/cover_letter success Single patches do not need cover letters
netdev/patch_count success Link
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 6 this patch: 6
netdev/cc_maintainers warning 6 maintainers not CCed: pabeni@redhat.com tglx@linutronix.de fw@strlen.de xiangxia.m.yue@gmail.com yangbo.lu@nxp.com aahringo@redhat.com
netdev/build_clang success Errors and warnings before: 22 this patch: 22
netdev/module_param success Was 0 now: 0
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/verify_fixes success Fixes tag looks correct
netdev/build_allmodconfig_warn success Errors and warnings before: 10 this patch: 10
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 8 lines checked
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0

Commit Message

Eric Dumazet Nov. 3, 2021, 11:49 p.m. UTC 
From: Eric Dumazet <edumazet@google.com>

Sanity check in sock_reserve_memory() was not enough to prevent malicious
user to trigger a NULL deref.

In this case, the isse is that sk_prot->memory_allocated is NULL.

Use standard sk_has_account() helper to deal with this.

BUG: KASAN: null-ptr-deref in instrument_atomic_read_write include/linux/instrumented.h:101 [inline]
BUG: KASAN: null-ptr-deref in atomic_long_add_return include/linux/atomic/atomic-instrumented.h:1218 [inline]
BUG: KASAN: null-ptr-deref in sk_memory_allocated_add include/net/sock.h:1371 [inline]
BUG: KASAN: null-ptr-deref in sock_reserve_memory net/core/sock.c:994 [inline]
BUG: KASAN: null-ptr-deref in sock_setsockopt+0x22ab/0x2b30 net/core/sock.c:1443
Write of size 8 at addr 0000000000000000 by task syz-executor.0/11270

CPU: 1 PID: 11270 Comm: syz-executor.0 Not tainted 5.15.0-syzkaller #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
 __kasan_report mm/kasan/report.c:446 [inline]
 kasan_report.cold+0x66/0xdf mm/kasan/report.c:459
 check_region_inline mm/kasan/generic.c:183 [inline]
 kasan_check_range+0x13d/0x180 mm/kasan/generic.c:189
 instrument_atomic_read_write include/linux/instrumented.h:101 [inline]
 atomic_long_add_return include/linux/atomic/atomic-instrumented.h:1218 [inline]
 sk_memory_allocated_add include/net/sock.h:1371 [inline]
 sock_reserve_memory net/core/sock.c:994 [inline]
 sock_setsockopt+0x22ab/0x2b30 net/core/sock.c:1443
 __sys_setsockopt+0x4f8/0x610 net/socket.c:2172
 __do_sys_setsockopt net/socket.c:2187 [inline]
 __se_sys_setsockopt net/socket.c:2184 [inline]
 __x64_sys_setsockopt+0xba/0x150 net/socket.c:2184
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7f56076d5ae9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f5604c4b188 EFLAGS: 00000246 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 00007f56077e8f60 RCX: 00007f56076d5ae9
RDX: 0000000000000049 RSI: 0000000000000001 RDI: 0000000000000003
RBP: 00007f560772ff25 R08: 000000000000fec7 R09: 0000000000000000
R10: 0000000020000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fffb61a100f R14: 00007f5604c4b300 R15: 0000000000022000
 </TASK>

Fixes: 2bb2f5fb21b0 ("net: add new socket option SO_RESERVE_MEM")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Acked-by: Wei Wang <weiwan@google.com>
---
 net/core/sock.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

patchwork-bot+netdevbpf@kernel.org Nov. 4, 2021, 11:30 a.m. UTC | #1 
Hello:

This patch was applied to netdev/net.git (master)
by David S. Miller <davem@davemloft.net>:

On Wed,  3 Nov 2021 16:49:11 -0700 you wrote:
> From: Eric Dumazet <edumazet@google.com>
> 
> Sanity check in sock_reserve_memory() was not enough to prevent malicious
> user to trigger a NULL deref.
> 
> In this case, the isse is that sk_prot->memory_allocated is NULL.
> 
> [...]

Here is the summary with links:
  - [net] net: fix possible NULL deref in sock_reserve_memory
    https://git.kernel.org/netdev/net/c/d00c8ee31729

You are awesome, thank you!
diff mbox series

Patch

diff --git a/net/core/sock.c b/net/core/sock.c
index 9862eefce21ede8644f84c99c539643ec31c7908..8f2b2f2c0e7b1decdb4a5c8d86327ed7caa62c99 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -976,7 +976,7 @@  static int sock_reserve_memory(struct sock *sk, int bytes)
 	bool charged;
 	int pages;
 
-	if (!mem_cgroup_sockets_enabled || !sk->sk_memcg)
+	if (!mem_cgroup_sockets_enabled || !sk->sk_memcg || !sk_has_account(sk))
 		return -EOPNOTSUPP;
 
 	if (!bytes)