lkml.org 
[lkml]   [2020]   [Jan]   [24]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH AUTOSEL 4.19 48/56] netfilter: nf_tables: store transaction list locally while requesting module
    Date
    From: Pablo Neira Ayuso <pablo@netfilter.org>

    [ Upstream commit ec7470b834fe7b5d7eff11b6677f5d7fdf5e9a91 ]

    This patch fixes a WARN_ON in nft_set_destroy() due to missing
    set reference count drop from the preparation phase. This is triggered
    by the module autoload path. Do not exercise the abort path from
    nft_request_module() while preparation phase cleaning up is still
    pending.

    WARNING: CPU: 3 PID: 3456 at net/netfilter/nf_tables_api.c:3740 nft_set_destroy+0x45/0x50 [nf_tables]
    [...]
    CPU: 3 PID: 3456 Comm: nft Not tainted 5.4.6-arch3-1 #1
    RIP: 0010:nft_set_destroy+0x45/0x50 [nf_tables]
    Code: e8 30 eb 83 c6 48 8b 85 80 00 00 00 48 8b b8 90 00 00 00 e8 dd 6b d7 c5 48 8b 7d 30 e8 24 dd eb c5 48 89 ef 5d e9 6b c6 e5 c5 <0f> 0b c3 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 8b 7f 10 e9 52
    RSP: 0018:ffffac4f43e53700 EFLAGS: 00010202
    RAX: 0000000000000001 RBX: ffff99d63a154d80 RCX: 0000000001f88e03
    RDX: 0000000001f88c03 RSI: ffff99d6560ef0c0 RDI: ffff99d63a101200
    RBP: ffff99d617721de0 R08: 0000000000000000 R09: 0000000000000318
    R10: 00000000f0000000 R11: 0000000000000001 R12: ffffffff880fabf0
    R13: dead000000000122 R14: dead000000000100 R15: ffff99d63a154d80
    FS: 00007ff3dbd5b740(0000) GS:ffff99d6560c0000(0000) knlGS:0000000000000000
    CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
    CR2: 00001cb5de6a9000 CR3: 000000016eb6a004 CR4: 00000000001606e0
    Call Trace:
    __nf_tables_abort+0x3e3/0x6d0 [nf_tables]
    nft_request_module+0x6f/0x110 [nf_tables]
    nft_expr_type_request_module+0x28/0x50 [nf_tables]
    nf_tables_expr_parse+0x198/0x1f0 [nf_tables]
    nft_expr_init+0x3b/0xf0 [nf_tables]
    nft_dynset_init+0x1e2/0x410 [nf_tables]
    nf_tables_newrule+0x30a/0x930 [nf_tables]
    nfnetlink_rcv_batch+0x2a0/0x640 [nfnetlink]
    nfnetlink_rcv+0x125/0x171 [nfnetlink]
    netlink_unicast+0x179/0x210
    netlink_sendmsg+0x208/0x3d0
    sock_sendmsg+0x5e/0x60
    ____sys_sendmsg+0x21b/0x290

    Update comment on the code to describe the new behaviour.

    Reported-by: Marco Oliverio <marco.oliverio@tanaza.com>
    Fixes: 452238e8d5ff ("netfilter: nf_tables: add and use helper for module autoload")
    Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    net/netfilter/nf_tables_api.c | 19 ++++++++++---------
    1 file changed, 10 insertions(+), 9 deletions(-)

    diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
    index 4711a8b56f32f..f7d1f66b29483 100644
    --- a/net/netfilter/nf_tables_api.c
    +++ b/net/netfilter/nf_tables_api.c
    @@ -483,23 +483,21 @@ __nf_tables_chain_type_lookup(const struct nlattr *nla, u8 family)
    }

    /*
    - * Loading a module requires dropping mutex that guards the
    - * transaction.
    - * We first need to abort any pending transactions as once
    - * mutex is unlocked a different client could start a new
    - * transaction. It must not see any 'future generation'
    - * changes * as these changes will never happen.
    + * Loading a module requires dropping mutex that guards the transaction.
    + * A different client might race to start a new transaction meanwhile. Zap the
    + * list of pending transaction and then restore it once the mutex is grabbed
    + * again. Users of this function return EAGAIN which implicitly triggers the
    + * transaction abort path to clean up the list of pending transactions.
    */
    #ifdef CONFIG_MODULES
    -static int __nf_tables_abort(struct net *net);
    -
    static void nft_request_module(struct net *net, const char *fmt, ...)
    {
    char module_name[MODULE_NAME_LEN];
    + LIST_HEAD(commit_list);
    va_list args;
    int ret;

    - __nf_tables_abort(net);
    + list_splice_init(&net->nft.commit_list, &commit_list);

    va_start(args, fmt);
    ret = vsnprintf(module_name, MODULE_NAME_LEN, fmt, args);
    @@ -510,6 +508,9 @@ static void nft_request_module(struct net *net, const char *fmt, ...)
    mutex_unlock(&net->nft.commit_mutex);
    request_module("%s", module_name);
    mutex_lock(&net->nft.commit_mutex);
    +
    + WARN_ON_ONCE(!list_empty(&net->nft.commit_list));
    + list_splice(&commit_list, &net->nft.commit_list);
    }
    #endif

    --
    2.20.1
    \
     
     \ /
      Last update: 2020-01-24 15:28    [W:5.683 / U:0.092 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site