lkml.org 
[lkml]   [2018]   [Apr]   [11]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 4.9 285/310] sctp: do not leak kernel memory to user space
    Date
    4.9-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Eric Dumazet <edumazet@google.com>


    [ Upstream commit 6780db244d6b1537d139dea0ec8aad10cf9e4adb ]

    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: 1da177e4c3f4 ("Linux-2.6.12-rc2")
    Signed-off-by: Eric Dumazet <edumazet@google.com>
    Cc: Vlad Yasevich <vyasevich@gmail.com>
    Cc: Neil Horman <nhorman@tuxdriver.com>
    Reported-by: syzbot <syzkaller@googlegroups.com>
    Signed-off-by: David S. Miller <davem@davemloft.net>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    ---
    net/sctp/ipv6.c | 4 +++-
    1 file changed, 3 insertions(+), 1 deletion(-)

    --- a/net/sctp/ipv6.c
    +++ b/net/sctp/ipv6.c
    @@ -727,8 +727,10 @@ static int sctp_v6_addr_to_user(struct s
    sctp_v6_map_v4(addr);
    }

    - if (addr->sa.sa_family == AF_INET)
    + if (addr->sa.sa_family == AF_INET) {
    + memset(addr->v4.sin_zero, 0, sizeof(addr->v4.sin_zero));
    return sizeof(struct sockaddr_in);
    + }
    return sizeof(struct sockaddr_in6);
    }


    \
     
     \ /
      Last update: 2018-04-11 21:12    [W:4.131 / U:0.008 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site