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    Contents of /trunk/kernel26-magellan/patches-2.6.16-r10/0129-2.6.16.15-SCTP-deadlock-CVE-2006-2275.patch

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    Revision 70 - (show annotations) (download)
    Thu May 11 19:09:22 2006 UTC (18 years ago) by niro
    File size: 5187 byte(s) 
    import
    1 From: Neil Horman <nhorman@tuxdriver.com>
    2 Date: Sat, 6 May 2006 00:02:09 +0000 (-0700)
    3 Subject: [PATCH] SCTP: Allow spillover of receive buffer to avoid deadlock. (CVE-2006-2275)
    4 X-Git-Url: http://www.kernel.org/git/?p=linux/kernel/git/stable/linux-2.6.16.y.git;a=commitdiff;h=2e2a2cd09dd7b3fbc99a1879a54090fd6db16f0c
    5
    6 [PATCH] SCTP: Allow spillover of receive buffer to avoid deadlock. (CVE-2006-2275)
    7
    8 This patch fixes a deadlock situation in the receive path by allowing
    9 temporary spillover of the receive buffer.
    10
    11 - If the chunk we receive has a tsn that immediately follows the ctsn,
    12 accept it even if we run out of receive buffer space and renege data with
    13 higher TSNs.
    14 - Once we accept one chunk in a packet, accept all the remaining chunks
    15 even if we run out of receive buffer space.
    16
    17 Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
    18 Acked-by: Mark Butler <butlerm@middle.net>
    19 Acked-by: Vlad Yasevich <vladislav.yasevich@hp.com>
    20 Signed-off-by: Sridhar Samudrala <sri@us.ibm.com>
    21 Signed-off-by: David S. Miller <davem@davemloft.net>
    22 Signed-off-by: Chris Wright <chrisw@sous-sol.org>
    23 ---
    24
    25 --- a/include/net/sctp/structs.h
    26 +++ b/include/net/sctp/structs.h
    27 @@ -702,6 +702,7 @@ struct sctp_chunk {
    28 __u8 tsn_gap_acked; /* Is this chunk acked by a GAP ACK? */
    29 __s8 fast_retransmit; /* Is this chunk fast retransmitted? */
    30 __u8 tsn_missing_report; /* Data chunk missing counter. */
    31 + __u8 data_accepted; /* At least 1 chunk in this packet accepted */
    32 };
    33
    34 void sctp_chunk_hold(struct sctp_chunk *);
    35 --- a/net/sctp/inqueue.c
    36 +++ b/net/sctp/inqueue.c
    37 @@ -149,6 +149,7 @@ struct sctp_chunk *sctp_inq_pop(struct s
    38 /* This is the first chunk in the packet. */
    39 chunk->singleton = 1;
    40 ch = (sctp_chunkhdr_t *) chunk->skb->data;
    41 + chunk->data_accepted = 0;
    42 }
    43
    44 chunk->chunk_hdr = ch;
    45 --- a/net/sctp/sm_statefuns.c
    46 +++ b/net/sctp/sm_statefuns.c
    47 @@ -5154,7 +5154,9 @@ static int sctp_eat_data(const struct sc
    48 int tmp;
    49 __u32 tsn;
    50 int account_value;
    51 + struct sctp_tsnmap *map = (struct sctp_tsnmap *)&asoc->peer.tsn_map;
    52 struct sock *sk = asoc->base.sk;
    53 + int rcvbuf_over = 0;
    54
    55 data_hdr = chunk->subh.data_hdr = (sctp_datahdr_t *)chunk->skb->data;
    56 skb_pull(chunk->skb, sizeof(sctp_datahdr_t));
    57 @@ -5165,10 +5167,16 @@ static int sctp_eat_data(const struct sc
    58 /* ASSERT: Now skb->data is really the user data. */
    59
    60 /*
    61 - * if we are established, and we have used up our receive
    62 - * buffer memory, drop the frame
    63 + * If we are established, and we have used up our receive buffer
    64 + * memory, think about droping the frame.
    65 + * Note that we have an opportunity to improve performance here.
    66 + * If we accept one chunk from an skbuff, we have to keep all the
    67 + * memory of that skbuff around until the chunk is read into user
    68 + * space. Therefore, once we accept 1 chunk we may as well accept all
    69 + * remaining chunks in the skbuff. The data_accepted flag helps us do
    70 + * that.
    71 */
    72 - if (asoc->state == SCTP_STATE_ESTABLISHED) {
    73 + if ((asoc->state == SCTP_STATE_ESTABLISHED) && (!chunk->data_accepted)) {
    74 /*
    75 * If the receive buffer policy is 1, then each
    76 * association can allocate up to sk_rcvbuf bytes
    77 @@ -5179,9 +5187,25 @@ static int sctp_eat_data(const struct sc
    78 account_value = atomic_read(&asoc->rmem_alloc);
    79 else
    80 account_value = atomic_read(&sk->sk_rmem_alloc);
    81 -
    82 - if (account_value > sk->sk_rcvbuf)
    83 - return SCTP_IERROR_IGNORE_TSN;
    84 + if (account_value > sk->sk_rcvbuf) {
    85 + /*
    86 + * We need to make forward progress, even when we are
    87 + * under memory pressure, so we always allow the
    88 + * next tsn after the ctsn ack point to be accepted.
    89 + * This lets us avoid deadlocks in which we have to
    90 + * drop frames that would otherwise let us drain the
    91 + * receive queue.
    92 + */
    93 + if ((sctp_tsnmap_get_ctsn(map) + 1) != tsn)
    94 + return SCTP_IERROR_IGNORE_TSN;
    95 +
    96 + /*
    97 + * We're going to accept the frame but we should renege
    98 + * to make space for it. This will send us down that
    99 + * path later in this function.
    100 + */
    101 + rcvbuf_over = 1;
    102 + }
    103 }
    104
    105 /* Process ECN based congestion.
    106 @@ -5229,6 +5253,7 @@ static int sctp_eat_data(const struct sc
    107 datalen -= sizeof(sctp_data_chunk_t);
    108
    109 deliver = SCTP_CMD_CHUNK_ULP;
    110 + chunk->data_accepted = 1;
    111
    112 /* Think about partial delivery. */
    113 if ((datalen >= asoc->rwnd) && (!asoc->ulpq.pd_mode)) {
    114 @@ -5245,7 +5270,8 @@ static int sctp_eat_data(const struct sc
    115 * large spill over.
    116 */
    117 if (!asoc->rwnd || asoc->rwnd_over ||
    118 - (datalen > asoc->rwnd + asoc->frag_point)) {
    119 + (datalen > asoc->rwnd + asoc->frag_point) ||
    120 + rcvbuf_over) {
    121
    122 /* If this is the next TSN, consider reneging to make
    123 * room. Note: Playing nice with a confused sender. A
    124 @@ -5253,8 +5279,8 @@ static int sctp_eat_data(const struct sc
    125 * space and in the future we may want to detect and
    126 * do more drastic reneging.
    127 */
    128 - if (sctp_tsnmap_has_gap(&asoc->peer.tsn_map) &&
    129 - (sctp_tsnmap_get_ctsn(&asoc->peer.tsn_map) + 1) == tsn) {
    130 + if (sctp_tsnmap_has_gap(map) &&
    131 + (sctp_tsnmap_get_ctsn(map) + 1) == tsn) {
    132 SCTP_DEBUG_PRINTK("Reneging for tsn:%u\n", tsn);
    133 deliver = SCTP_CMD_RENEGE;
    134 } else {