CVE-2022-48781

In the Linux kernel, the following vulnerability has been resolved:

crypto: af_alg - get rid of alg_memory_allocated

alg_memory_allocated does not seem to be really used.

alg_proto does have a .memory_allocated field, but no corresponding .sysctl_mem.

This means sk_has_account() returns true, but all sk_prot_mem_limits() users will trigger a NULL dereference [1].

THis was not a problem until SO_RESERVE_MEM addition.

general protection fault, probably for non-canonical address 0xdffffc0000000001: 0000 [#1] PREEMPT SMP KASAN KASAN: null-ptr-deref in range [0x0000000000000008-0x000000000000000f] CPU: 1 PID: 3591 Comm: syz-executor153 Not tainted 5.17.0-rc3-syzkaller-00316-gb81b1829e7e3 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:sk_prot_mem_limits include/net/sock.h:1523 [inline] RIP: 0010:sock_reserve_memory+0x1d7/0x330 net/core/sock.c:1000 Code: 08 00 74 08 48 89 ef e8 27 20 bb f9 4c 03 7c 24 10 48 8b 6d 00 48 83 c5 08 48 89 e8 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df <80> 3c 08 00 74 08 48 89 ef e8 fb 1f bb f9 48 8b 6d 00 4c 89 ff 48 RSP: 0018:ffffc90001f1fb68 EFLAGS: 00010202 RAX: 0000000000000001 RBX: ffff88814aabc000 RCX: dffffc0000000000 RDX: 0000000000000001 RSI: 0000000000000008 RDI: ffffffff90e18120 RBP: 0000000000000008 R08: dffffc0000000000 R09: fffffbfff21c3025 R10: fffffbfff21c3025 R11: 0000000000000000 R12: ffffffff8d109840 R13: 0000000000001002 R14: 0000000000000001 R15: 0000000000000001 FS: 0000555556e08300(0000) GS:ffff8880b9b00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fc74416f130 CR3: 0000000073d9e000 CR4: 00000000003506e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: sock_setsockopt+0x14a9/0x3a30 net/core/sock.c:1446 __sys_setsockopt+0x5af/0x980 net/socket.c:2176 __do_sys_setsockopt net/socket.c:2191 [inline] __se_sys_setsockopt net/socket.c:2188 [inline] __x64_sys_setsockopt+0xb1/0xc0 net/socket.c:2188 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7fc7440fddc9 Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 51 15 00 00 90 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 c0 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ffe98f07968 EFLAGS: 00000246 ORIG_RAX: 0000000000000036 RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007fc7440fddc9 RDX: 0000000000000049 RSI: 0000000000000001 RDI: 0000000000000004 RBP: 0000000000000000 R08: 0000000000000004 R09: 00007ffe98f07990 R10: 0000000020000000 R11: 0000000000000246 R12: 00007ffe98f0798c R13: 00007ffe98f079a0 R14: 00007ffe98f079e0 R15: 0000000000000000 Modules linked in: —[ end trace 0000000000000000 ]— RIP: 0010:sk_prot_mem_limits include/net/sock.h:1523 [inline] RIP: 0010:sock_reserve_memory+0x1d7/0x330 net/core/sock.c:1000 Code: 08 00 74 08 48 89 ef e8 27 20 bb f9 4c 03 7c 24 10 48 8b 6d 00 48 83 c5 08 48 89 e8 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df <80> 3c 08 00 74 08 48 89 ef e8 fb 1f bb f9 48 8b 6d 00 4c 89 ff 48 RSP: 0018:ffffc90001f1fb68 EFLAGS: 00010202 RAX: 0000000000000001 RBX: ffff88814aabc000 RCX: dffffc0000000000 RDX: 0000000000000001 RSI: 0000000000000008 RDI: ffffffff90e18120 RBP: 0000000000000008 R08: dffffc0000000000 R09: fffffbfff21c3025 R10: fffffbfff21c3025 R11: 0000000000000000 R12: ffffffff8d109840 R13: 0000000000001002 R14: 0000000000000001 R15: 0000000000000001 FS: 0000555556e08300(0000) GS:ffff8880b9b00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fc74416f130 CR3: 0000000073d9e000 CR4: 00000000003506e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000

Weakness

A NULL pointer dereference occurs when the application dereferences a pointer that it expects to be valid, but is NULL, typically causing a crash or exit.

Affected Software

Potential Mitigations

References

• https://git.kernel.org/stable/c/25206111512de994dfc914f5b2972a22aa904ef3
• https://git.kernel.org/stable/c/9d06f489b9e901580159e21fdc29f73df7ed08dc