Messages in this thread | | | Date | Wed, 16 Jul 2008 19:12:01 +0300 | From | "Nick Kossifidis" <> | Subject | Re: [PATCH 1/5] Ath5k: fix memory corruption |
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2008/7/15 Jiri Slaby <jirislaby@gmail.com>: > When signal is noisy, hardware can use all RX buffers and since the last > entry in the list is self-linked, it overwrites the entry until we link > new buffers. > > Ensure that we don't free this last one until we are 100% sure that it > is not used by the hardware anymore to not cause memory curruption as > can be seen below. > > This is done by checking next buffer in the list. Even after that we > know that the hardware refetched the new link and proceeded further > (the next buffer is ready) we can finally free the overwritten buffer. > > We discard it since the status in its descriptor is overwritten (OR-ed > by new status) too. > > ============================================================================= > BUG kmalloc-4096: Poison overwritten > ----------------------------------------------------------------------------- > > INFO: 0xffff810067419060-0xffff810067419667. First byte 0x8 instead of 0x6b > INFO: Allocated in dev_alloc_skb+0x18/0x30 age=1118 cpu=1 pid=0 > INFO: Freed in skb_release_data+0x85/0xd0 age=1105 cpu=1 pid=3718 > INFO: Slab 0xffffe200019d0600 objects=7 used=0 fp=0xffff810067419048 flags=0x40000000000020c3 > INFO: Object 0xffff810067419048 @offset=4168 fp=0xffff81006741c120 > > Bytes b4 0xffff810067419038: 4f 0b 02 00 01 00 00 00 5a 5a 5a 5a 5a 5a 5a 5a O.......ZZZZZZZZ > Object 0xffff810067419048: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkkkkkkkkkkkkkk > Object 0xffff810067419058: 6b 6b 6b 6b 6b 6b 6b 6b 08 42 30 00 00 0b 6b 80 kkkkkkkk.B0...k. > Object 0xffff810067419068: f0 5d 00 4f 62 08 a3 64 00 0c 42 16 52 e4 f0 5a 360].Ob.243d..B.R344360Z > Object 0xffff810067419078: 68 81 00 00 7b a5 b4 be 7d 3b 8f 53 cd d5 de 12 h...{245264276};.S315325336. > Object 0xffff810067419088: 96 10 0b 89 48 54 23 41 0f 4e 2d b9 37 c3 cb 29 ....HT#A.N-2717303313) > Object 0xffff810067419098: d1 e0 de 14 8a 57 2a cc 3b 44 0d 78 7a 19 12 15 321340336..W*314;D.xz... > Object 0xffff8100674190a8: a9 ec d4 35 a8 10 ec 8c 40 a7 06 0a 51 a7 48 bb 2513543245250.354.@247..Q247H273 > Object 0xffff8100674190b8: 3e cf a1 c7 38 60 63 3f 51 15 c7 20 eb ba 65 30 >ϡ3078`c?Q.307.353272e0 > Redzone 0xffff81006741a048: bb bb bb bb bb bb bb bb 273273273273273273273273 > Padding 0xffff81006741a088: 5a 5a 5a 5a 5a 5a 5a 5a ZZZZZZZZ > Pid: 3297, comm: ath5k_pci Not tainted 2.6.26-rc8-mm1_64 #427 > > Call Trace: > [<ffffffff802a7306>] print_trailer+0xf6/0x150 > [<ffffffff802a7485>] check_bytes_and_report+0x125/0x180 > [<ffffffff802a75dc>] check_object+0xac/0x260 > [<ffffffff802a9308>] __slab_alloc+0x368/0x6d0 > [<ffffffff80544f82>] ? wireless_send_event+0x142/0x310 > [<ffffffff804b1bd4>] ? __alloc_skb+0x44/0x150 > [<ffffffff80544f82>] ? wireless_send_event+0x142/0x310 > [<ffffffff802aa853>] __kmalloc_track_caller+0xc3/0xf0 > [<ffffffff804b1bfe>] __alloc_skb+0x6e/0x150 > [... stack snipped] > > FIX kmalloc-4096: Restoring 0xffff810067419060-0xffff810067419667=0x6b > > FIX kmalloc-4096: Marking all objects used > > Signed-off-by: Jiri Slaby <jirislaby@gmail.com> > Cc: Nick Kossifidis <mickflemm@gmail.com> > Cc: Luis R. Rodriguez <mcgrof@gmail.com> > --- > drivers/net/wireless/ath5k/base.c | 32 +++++++++++++++++++++++++------- > drivers/net/wireless/ath5k/base.h | 2 +- > 2 files changed, 26 insertions(+), 8 deletions(-) > > diff --git a/drivers/net/wireless/ath5k/base.c b/drivers/net/wireless/ath5k/base.c > index 12a9443..e9ec284 100644 > --- a/drivers/net/wireless/ath5k/base.c > +++ b/drivers/net/wireless/ath5k/base.c > @@ -1683,20 +1683,21 @@ ath5k_tasklet_rx(unsigned long data) > struct ath5k_rx_status rs = {}; > struct sk_buff *skb; > struct ath5k_softc *sc = (void *)data; > - struct ath5k_buf *bf; > + struct ath5k_buf *bf, *bf_last; > struct ath5k_desc *ds; > int ret; > int hdrlen; > int pad; > > spin_lock(&sc->rxbuflock); > + if (list_empty(&sc->rxbuf)) { > + ATH5K_WARN(sc, "empty rx buf pool\n"); > + goto unlock; > + } > + bf_last = list_entry(sc->rxbuf.prev, struct ath5k_buf, list); > do { > rxs.flag = 0; > > - if (unlikely(list_empty(&sc->rxbuf))) { > - ATH5K_WARN(sc, "empty rx buf pool\n"); > - break; > - } > bf = list_first_entry(&sc->rxbuf, struct ath5k_buf, list); > BUG_ON(bf->skb == NULL); > skb = bf->skb; > @@ -1706,8 +1707,24 @@ ath5k_tasklet_rx(unsigned long data) > pci_dma_sync_single_for_cpu(sc->pdev, sc->desc_daddr, > sc->desc_len, PCI_DMA_FROMDEVICE); > > - if (unlikely(ds->ds_link == bf->daddr)) /* this is the end */ > - break; > + /* > + * last buffer must not be freed to ensure proper hardware > + * function. When the hardware finishes also a packet next to > + * it, we are sure, it doesn't use it anymore and we can go on. > + */ > + if (bf_last == bf) > + bf->flags |= 1; > + if (bf->flags) { > + struct ath5k_buf *bf_next = list_entry(bf->list.next, > + struct ath5k_buf, list); > + ret = sc->ah->ah_proc_rx_desc(sc->ah, bf_next->desc, > + &rs); > + if (ret) > + break; > + bf->flags &= ~1; > + /* skip the overwritten one (even status is martian) */ > + goto next; > + } > > ret = sc->ah->ah_proc_rx_desc(sc->ah, ds, &rs); > if (unlikely(ret == -EINPROGRESS)) > @@ -1817,6 +1834,7 @@ accept: > next: > list_move_tail(&bf->list, &sc->rxbuf); > } while (ath5k_rxbuf_setup(sc, bf) == 0); > +unlock: > spin_unlock(&sc->rxbuflock); > } > > diff --git a/drivers/net/wireless/ath5k/base.h b/drivers/net/wireless/ath5k/base.h > index 47f414b..d7e03e6 100644 > --- a/drivers/net/wireless/ath5k/base.h > +++ b/drivers/net/wireless/ath5k/base.h > @@ -56,7 +56,7 @@ > > struct ath5k_buf { > struct list_head list; > - unsigned int flags; /* tx descriptor flags */ > + unsigned int flags; /* rx descriptor flags */ > struct ath5k_desc *desc; /* virtual addr of desc */ > dma_addr_t daddr; /* physical addr of desc */ > struct sk_buff *skb; /* skbuff for buf */ > -- > 1.5.6.2 > >
Nice catch ;-)
Acked-by: Nick Kossifidis <mickflemm@gmail.com>
-- GPG ID: 0xD21DB2DB As you read this post global entropy rises. Have Fun ;-) Nick
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