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| author | David Howells <dhowells@redhat.com> | 2020-01-24 23:08:04 +0000 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2020-01-27 10:56:30 +0100 |
| commit | 122d74fac84204b9a98263636f6f9a3b2e665639 (patch) | |
| tree | 0adfab85c39f687d872855040dd33a4d2ba029e0 /net/rxrpc | |
| parent | 55cd9f67f1e45de8517cdaab985fb8e56c0bc1d8 (diff) | |
| download | lwn-122d74fac84204b9a98263636f6f9a3b2e665639.tar.gz lwn-122d74fac84204b9a98263636f6f9a3b2e665639.zip | |
rxrpc: Fix use-after-free in rxrpc_receive_data()
The subpacket scanning loop in rxrpc_receive_data() references the
subpacket count in the private data part of the sk_buff in the loop
termination condition. However, when the final subpacket is pasted into
the ring buffer, the function is no longer has a ref on the sk_buff and
should not be looking at sp->* any more. This point is actually marked in
the code when skb is cleared (but sp is not - which is an error).
Fix this by caching sp->nr_subpackets in a local variable and using that
instead.
Also clear 'sp' to catch accesses after that point.
This can show up as an oops in rxrpc_get_skb() if sp->nr_subpackets gets
trashed by the sk_buff getting freed and reused in the meantime.
Fixes: e2de6c404898 ("rxrpc: Use info in skbuff instead of reparsing a jumbo packet")
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/rxrpc')
| -rw-r--r-- | net/rxrpc/input.c | 12 |
1 files changed, 7 insertions, 5 deletions
diff --git a/net/rxrpc/input.c b/net/rxrpc/input.c index 86bd133b4fa0..96d54e5bf7bc 100644 --- a/net/rxrpc/input.c +++ b/net/rxrpc/input.c @@ -413,7 +413,7 @@ static void rxrpc_input_data(struct rxrpc_call *call, struct sk_buff *skb) { struct rxrpc_skb_priv *sp = rxrpc_skb(skb); enum rxrpc_call_state state; - unsigned int j; + unsigned int j, nr_subpackets; rxrpc_serial_t serial = sp->hdr.serial, ack_serial = 0; rxrpc_seq_t seq0 = sp->hdr.seq, hard_ack; bool immediate_ack = false, jumbo_bad = false; @@ -457,7 +457,8 @@ static void rxrpc_input_data(struct rxrpc_call *call, struct sk_buff *skb) call->ackr_prev_seq = seq0; hard_ack = READ_ONCE(call->rx_hard_ack); - if (sp->nr_subpackets > 1) { + nr_subpackets = sp->nr_subpackets; + if (nr_subpackets > 1) { if (call->nr_jumbo_bad > 3) { ack = RXRPC_ACK_NOSPACE; ack_serial = serial; @@ -465,11 +466,11 @@ static void rxrpc_input_data(struct rxrpc_call *call, struct sk_buff *skb) } } - for (j = 0; j < sp->nr_subpackets; j++) { + for (j = 0; j < nr_subpackets; j++) { rxrpc_serial_t serial = sp->hdr.serial + j; rxrpc_seq_t seq = seq0 + j; unsigned int ix = seq & RXRPC_RXTX_BUFF_MASK; - bool terminal = (j == sp->nr_subpackets - 1); + bool terminal = (j == nr_subpackets - 1); bool last = terminal && (sp->rx_flags & RXRPC_SKB_INCL_LAST); u8 flags, annotation = j; @@ -506,7 +507,7 @@ static void rxrpc_input_data(struct rxrpc_call *call, struct sk_buff *skb) } if (call->rxtx_buffer[ix]) { - rxrpc_input_dup_data(call, seq, sp->nr_subpackets > 1, + rxrpc_input_dup_data(call, seq, nr_subpackets > 1, &jumbo_bad); if (ack != RXRPC_ACK_DUPLICATE) { ack = RXRPC_ACK_DUPLICATE; @@ -564,6 +565,7 @@ static void rxrpc_input_data(struct rxrpc_call *call, struct sk_buff *skb) * ring. */ skb = NULL; + sp = NULL; } if (last) { |