| Message ID | 20230213160059.3829741-1-edumazet@google.com (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 2558b8039d059342197610498c8749ad294adee5 |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [net] net: use a bounce buffer for copying skb->mark | expand |
From: Eric Dumazet <edumazet@google.com> Date: Mon, 13 Feb 2023 16:00:59 +0000 > 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) > > Fixes: 6fd1d51cfa25 ("net: SO_RCVMARK socket option for SO_MARK with recvmsg()") > Reported-by: syzbot <syzkaller@googlegroups.com> > Signed-off-by: Eric Dumazet <edumazet@google.com> > Cc: Erin MacNeil <lnx.erin@gmail.com> Reviewed-by: Alexander Lobakin <alexandr.lobakin@intel.com> > --- > net/socket.c | 9 ++++++--- > 1 file changed, 6 insertions(+), 3 deletions(-) > > diff --git a/net/socket.c b/net/socket.c > index 77626e4d96900b946e340e59e6984e5bab672bbe..4080b4ba7daf35a3a0b88a160299f4abd3afc88f 100644 > --- a/net/socket.c > +++ b/net/socket.c > @@ -982,9 +982,12 @@ static inline void sock_recv_drops(struct msghdr *msg, struct sock *sk, > static void sock_recv_mark(struct msghdr *msg, struct sock *sk, > struct sk_buff *skb) > { > - if (sock_flag(sk, SOCK_RCVMARK) && skb) > - put_cmsg(msg, SOL_SOCKET, SO_MARK, sizeof(__u32), > - &skb->mark); > + if (sock_flag(sk, SOCK_RCVMARK) && skb) { > + /* We must use a bounce buffer for CONFIG_HARDENED_USERCOPY=y */ > + __u32 mark = skb->mark; > + > + put_cmsg(msg, SOL_SOCKET, SO_MARK, sizeof(__u32), &mark); > + } > } > > void __sock_recv_cmsgs(struct msghdr *msg, struct sock *sk, Thanks, Olek
Hello: This patch was applied to netdev/net.git (master) by Jakub Kicinski <kuba@kernel.org>: On Mon, 13 Feb 2023 16:00:59 +0000 you wrote: > 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. > > [...] Here is the summary with links: - [net] net: use a bounce buffer for copying skb->mark https://git.kernel.org/netdev/net/c/2558b8039d05 You are awesome, thank you!
diff --git a/net/socket.c b/net/socket.c index 77626e4d96900b946e340e59e6984e5bab672bbe..4080b4ba7daf35a3a0b88a160299f4abd3afc88f 100644 --- a/net/socket.c +++ b/net/socket.c @@ -982,9 +982,12 @@ static inline void sock_recv_drops(struct msghdr *msg, struct sock *sk, static void sock_recv_mark(struct msghdr *msg, struct sock *sk, struct sk_buff *skb) { - if (sock_flag(sk, SOCK_RCVMARK) && skb) - put_cmsg(msg, SOL_SOCKET, SO_MARK, sizeof(__u32), - &skb->mark); + if (sock_flag(sk, SOCK_RCVMARK) && skb) { + /* We must use a bounce buffer for CONFIG_HARDENED_USERCOPY=y */ + __u32 mark = skb->mark; + + put_cmsg(msg, SOL_SOCKET, SO_MARK, sizeof(__u32), &mark); + } } void __sock_recv_cmsgs(struct msghdr *msg, struct sock *sk,
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) Fixes: 6fd1d51cfa25 ("net: SO_RCVMARK socket option for SO_MARK with recvmsg()") Reported-by: syzbot <syzkaller@googlegroups.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Erin MacNeil <lnx.erin@gmail.com> --- net/socket.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-)