• Eric Dumazet's avatar
    sctp: do not leak kernel memory to user space · 3f80d01b
    Eric Dumazet authored
    
    [ Upstream commit 6780db24 ]
    
    syzbot produced a nice report [1]
    
    Issue here is that a recvmmsg() managed to leak 8 bytes of kernel memory
    to user space, because sin_zero (padding field) was not properly cleared.
    
    [1]
    BUG: KMSAN: uninit-value in copy_to_user include/linux/uaccess.h:184 [inline]
    BUG: KMSAN: uninit-value in move_addr_to_user+0x32e/0x530 net/socket.c:227
    CPU: 1 PID: 3586 Comm: syzkaller481044 Not tainted 4.16.0+ #82
    Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
    Call Trace:
     __dump_stack lib/dump_stack.c:17 [inline]
     dump_stack+0x185/0x1d0 lib/dump_stack.c:53
     kmsan_report+0x142/0x240 mm/kmsan/kmsan.c:1067
     kmsan_internal_check_memory+0x164/0x1d0 mm/kmsan/kmsan.c:1176
     kmsan_copy_to_user+0x69/0x160 mm/kmsan/kmsan.c:1199
     copy_to_user include/linux/uaccess.h:184 [inline]
     move_addr_to_user+0x32e/0x530 net/socket.c:227
     ___sys_recvmsg+0x4e2/0x810 net/socket.c:2211
     __sys_recvmmsg+0x54e/0xdb0 net/socket.c:2313
     SYSC_recvmmsg+0x29b/0x3e0 net/socket.c:2394
     SyS_recvmmsg+0x76/0xa0 net/socket.c:2378
     do_syscall_64+0x309/0x430 arch/x86/entry/common.c:287
     entry_SYSCALL_64_after_hwframe+0x3d/0xa2
    RIP: 0033:0x4401c9
    RSP: 002b:00007ffc56f73098 EFLAGS: 00000217 ORIG_RAX: 000000000000012b
    RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 00000000004401c9
    RDX: 0000000000000001 RSI: 0000000020003ac0 RDI: 0000000000000003
    RBP: 00000000006ca018 R08: 0000000020003bc0 R09: 0000000000000010
    R10: 0000000000000000 R11: 0000000000000217 R12: 0000000000401af0
    R13: 0000000000401b80 R14: 0000000000000000 R15: 0000000000000000
    
    Local variable description: ----addr@___sys_recvmsg
    Variable was created at:
     ___sys_recvmsg+0xd5/0x810 net/socket.c:2172
     __sys_recvmmsg+0x54e/0xdb0 net/socket.c:2313
    
    Bytes 8-15 of 16 are uninitialized
    
    ==================================================================
    Kernel panic - not syncing: panic_on_warn set ...
    
    CPU: 1 PID: 3586 Comm: syzkaller481044 Tainted: G    B            4.16.0+ #82
    Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
    Call Trace:
     __dump_stack lib/dump_stack.c:17 [inline]
     dump_stack+0x185/0x1d0 lib/dump_stack.c:53
     panic+0x39d/0x940 kernel/panic.c:183
     kmsan_report+0x238/0x240 mm/kmsan/kmsan.c:1083
     kmsan_internal_check_memory+0x164/0x1d0 mm/kmsan/kmsan.c:1176
     kmsan_copy_to_user+0x69/0x160 mm/kmsan/kmsan.c:1199
     copy_to_user include/linux/uaccess.h:184 [inline]
     move_addr_to_user+0x32e/0x530 net/socket.c:227
     ___sys_recvmsg+0x4e2/0x810 net/socket.c:2211
     __sys_recvmmsg+0x54e/0xdb0 net/socket.c:2313
     SYSC_recvmmsg+0x29b/0x3e0 net/socket.c:2394
     SyS_recvmmsg+0x76/0xa0 net/socket.c:2378
     do_syscall_64+0x309/0x430 arch/x86/entry/common.c:287
     entry_SYSCALL_64_after_hwframe+0x3d/0xa2
    
    Fixes: 1da177e4 ("Linux-2.6.12-rc2")
    Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
    Cc:	Vlad Yasevich <vyasevich@gmail.com>
    Cc:	Neil Horman <nhorman@tuxdriver.com>
    Reported-by: default avatarsyzbot <syzkaller@googlegroups.com>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    3f80d01b
ipv6.c 29.5 KB