• Ido Schimmel's avatar
    ip6mr: Do not call __IP6_INC_STATS() from preemptible context · 8d3e7357
    Ido Schimmel authored
    BugLink: https://bugs.launchpad.net/bugs/1822271
    
    [ Upstream commit 87c11f1d ]
    
    Similar to commit 44f49dd8 ("ipmr: fix possible race resulting from
    improper usage of IP_INC_STATS_BH() in preemptible context."), we cannot
    assume preemption is disabled when incrementing the counter and
    accessing a per-CPU variable.
    
    Preemption can be enabled when we add a route in process context that
    corresponds to packets stored in the unresolved queue, which are then
    forwarded using this route [1].
    
    Fix this by using IP6_INC_STATS() which takes care of disabling
    preemption on architectures where it is needed.
    
    [1]
    [  157.451447] BUG: using __this_cpu_add() in preemptible [00000000] code: smcrouted/2314
    [  157.460409] caller is ip6mr_forward2+0x73e/0x10e0
    [  157.460434] CPU: 3 PID: 2314 Comm: smcrouted Not tainted 5.0.0-rc7-custom-03635-g22f2712113f1 #1336
    [  157.460449] Hardware name: Mellanox Technologies Ltd. MSN2100-CB2FO/SA001017, BIOS 5.6.5 06/07/2016
    [  157.460461] Call Trace:
    [  157.460486]  dump_stack+0xf9/0x1be
    [  157.460553]  check_preemption_disabled+0x1d6/0x200
    [  157.460576]  ip6mr_forward2+0x73e/0x10e0
    [  157.460705]  ip6_mr_forward+0x9a0/0x1510
    [  157.460771]  ip6mr_mfc_add+0x16b3/0x1e00
    [  157.461155]  ip6_mroute_setsockopt+0x3cb/0x13c0
    [  157.461384]  do_ipv6_setsockopt.isra.8+0x348/0x4060
    [  157.462013]  ipv6_setsockopt+0x90/0x110
    [  157.462036]  rawv6_setsockopt+0x4a/0x120
    [  157.462058]  __sys_setsockopt+0x16b/0x340
    [  157.462198]  __x64_sys_setsockopt+0xbf/0x160
    [  157.462220]  do_syscall_64+0x14d/0x610
    [  157.462349]  entry_SYSCALL_64_after_hwframe+0x49/0xbe
    
    Fixes: 0912ea38 ("[IPV6] MROUTE: Add stats in multicast routing module method ip6_mr_forward().")
    Signed-off-by: default avatarIdo Schimmel <idosch@mellanox.com>
    Reported-by: default avatarAmit Cohen <amitc@mellanox.com>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    Signed-off-by: default avatarStefan Bader <stefan.bader@canonical.com>
    Acked-by: default avatarJuerg Haefliger <juerg.haefliger@canonical.com>
    Signed-off-by: default avatarKleber Sacilotto de Souza <kleber.souza@canonical.com>
    8d3e7357
ip6mr.c 57.2 KB