Description

In the Linux kernel, the following vulnerability has been resolved: net: use a bounce buffer for copying skb->mark syzbot found arm64 builds would crash in sock_recv_mark() when CONFIG_HARDENED_USERCOPY=y x86 and powerpc are not detecting the issue because they define user_access_begin. This will be handled in a different patch, because a check_object_size() is missing. Only data from skb->cb[] can be copied directly to/from user space, as explained in commit 79a8a642bf05 ("net: Whitelist the skbuff_head_cache "cb" field") syzbot report was: usercopy: Kernel memory exposure attempt detected from SLUB object 'skbuff_head_cache' (offset 168, size 4)! ------------[ cut here ]------------ kernel BUG at mm/usercopy.c:102 ! Internal error: Oops - BUG: 00000000f2000800 [#1] PREEMPT SMP Modules linked in: CPU: 0 PID: 4410 Comm: syz-executor533 Not tainted 6.2.0-rc7-syzkaller-17907-g2d3827b3f393 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/21/2023 pstate: 60400005 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc : usercopy_abort+0x90/0x94 mm/usercopy.c:90 lr : usercopy_abort+0x90/0x94 mm/usercopy.c:90 sp : ffff80000fb9b9a0 x29: ffff80000fb9b9b0 x28: ffff0000c6073400 x27: 0000000020001a00 x26: 0000000000000014 x25: ffff80000cf52000 x24: fffffc0000000000 x23: 05ffc00000000200 x22: fffffc000324bf80 x21: ffff0000c92fe1a8 x20: 0000000000000001 x19: 0000000000000004 x18: 0000000000000000 x17: 656a626f2042554c x16: ffff0000c6073dd0 x15: ffff80000dbd2118 x14: ffff0000c6073400 x13: 00000000ffffffff x12: ffff0000c6073400 x11: ff808000081bbb4c x10: 0000000000000000 x9 : 7b0572d7cc0ccf00 x8 : 7b0572d7cc0ccf00 x7 : ffff80000bf650d4 x6 : 0000000000000000 x5 : 0000000000000001 x4 : 0000000000000001 x3 : 0000000000000000 x2 : ffff0001fefbff08 x1 : 0000000100000000 x0 : 000000000000006c Call trace: usercopy_abort+0x90/0x94 mm/usercopy.c:90 __check_heap_object+0xa8/0x100 mm/slub.c:4761 check_heap_object mm/usercopy.c:196 [inline] __check_object_size+0x208/0x6b8 mm/usercopy.c:251 check_object_size include/linux/thread_info.h:199 [inline] __copy_to_user include/linux/uaccess.h:115 [inline] put_cmsg+0x408/0x464 net/core/scm.c:238 sock_recv_mark net/socket.c:975 [inline] __sock_recv_cmsgs+0x1fc/0x248 net/socket.c:984 sock_recv_cmsgs include/net/sock.h:2728 [inline] packet_recvmsg+0x2d8/0x678 net/packet/af_packet.c:3482 ____sys_recvmsg+0x110/0x3a0 ___sys_recvmsg net/socket.c:2737 [inline] __sys_recvmsg+0x194/0x210 net/socket.c:2767 __do_sys_recvmsg net/socket.c:2777 [inline] __se_sys_recvmsg net/socket.c:2774 [inline] __arm64_sys_recvmsg+0x2c/0x3c net/socket.c:2774 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x64/0x178 arch/arm64/kernel/syscall.c:52 el0_svc_common+0xbc/0x180 arch/arm64/kernel/syscall.c:142 do_el0_svc+0x48/0x110 arch/arm64/kernel/syscall.c:193 el0_svc+0x58/0x14c arch/arm64/kernel/entry-common.c:637 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655 el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:591 Code: 91388800 aa0903e1 f90003e8 94e6d752 (d4210000)

Severity

 

CVSS Version 4.0 CVSS Version 3.x CVSS Version 2.0

CVSS 4.0 Severity and Metrics:

NIST: NVD

N/A

NVD assessment not yet provided.

NVD Analysts use publicly available information to associate vector strings and CVSS scores. We also display any CVSS information provided within the CVE List from the CNA.

Note: NVD Analysts have not published a CVSS score for this CVE at this time. NVD Analysts use publicly available information at the time of analysis to associate CVSS vector strings.

CVSS 3.x Severity and Metrics:

NIST: NVD

Base Score:  N/A

NVD assessment not yet provided.

NVD Analysts use publicly available information to associate vector strings and CVSS scores. We also display any CVSS information provided within the CVE List from the CNA.

Note: NVD Analysts have not published a CVSS score for this CVE at this time. NVD Analysts use publicly available information at the time of analysis to associate CVSS vector strings.

CVSS 2.0 Severity and Metrics:

NIST: NVD

Base Score: N/A

NVD assessment not yet provided.

NVD Analysts use publicly available information to associate vector strings and CVSS scores. We also display any CVSS information provided within the CVE List from the CNA.

Note: NVD Analysts have not published a CVSS score for this CVE at this time. NVD Analysts use publicly available information at the time of analysis to associate CVSS vector strings.

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

net: use a bounce buffer for copying skb->mark

syzbot found arm64 builds would crash in sock_recv_mark()
when CONFIG_HARDENED_USERCOPY=y

x86 and powerpc are not detecting the issue because
they define user_access_begin.
This will be handled in a different patch,
because a check_object_size() is missing.

Only data from skb->cb[] can be copied directly to/from user space,
as explained in commit 79a8a642bf05 ("net: Whitelist
th

kernel.org https://git.kernel.org/stable/c/2558b8039d059342197610498c8749ad294adee5 [No types assigned]

kernel.org https://git.kernel.org/stable/c/863a7de987f02a901bf215509276a7de0370e0f9 [No types assigned]