diff options
| author | Stefan Weil <sw@weilnetz.de> | 2015-11-20 08:42:33 +0100 |
|---|---|---|
| committer | Jason Wang <jasowang@redhat.com> | 2015-11-27 10:39:55 +0800 |
| commit | 00837731d254908a841d69298a4f9f077babaf24 (patch) | |
| tree | a98851621aabb53548d16f2288a8753a67801fc8 | |
| parent | b04fc428356a540fdb9065fa8c3c71ee476c2031 (diff) | |
| download | qemu-00837731d254908a841d69298a4f9f077babaf24.zip qemu-00837731d254908a841d69298a4f9f077babaf24.tar.gz qemu-00837731d254908a841d69298a4f9f077babaf24.tar.bz2 | |
eepro100: Prevent two endless loops
http://lists.nongnu.org/archive/html/qemu-devel/2015-11/msg04592.html
shows an example how an endless loop in function action_command can
be achieved.
During my code review, I noticed a 2nd case which can result in an
endless loop.
Reported-by: Qinghao Tang <luodalongde@gmail.com>
Signed-off-by: Stefan Weil <sw@weilnetz.de>
Signed-off-by: Jason Wang <jasowang@redhat.com>
| -rw-r--r-- | hw/net/eepro100.c | 16 |
1 files changed, 16 insertions, 0 deletions
diff --git a/hw/net/eepro100.c b/hw/net/eepro100.c index 60333b7..685a478 100644 --- a/hw/net/eepro100.c +++ b/hw/net/eepro100.c @@ -774,6 +774,11 @@ static void tx_command(EEPRO100State *s) #if 0 uint16_t tx_buffer_el = lduw_le_pci_dma(&s->dev, tbd_address + 6); #endif + if (tx_buffer_size == 0) { + /* Prevent an endless loop. */ + logout("loop in %s:%u\n", __FILE__, __LINE__); + break; + } tbd_address += 8; TRACE(RXTX, logout ("TBD (simplified mode): buffer address 0x%08x, size 0x%04x\n", @@ -855,6 +860,10 @@ static void set_multicast_list(EEPRO100State *s) static void action_command(EEPRO100State *s) { + /* The loop below won't stop if it gets special handcrafted data. + Therefore we limit the number of iterations. */ + unsigned max_loop_count = 16; + for (;;) { bool bit_el; bool bit_s; @@ -870,6 +879,13 @@ static void action_command(EEPRO100State *s) #if 0 bool bit_sf = ((s->tx.command & COMMAND_SF) != 0); #endif + + if (max_loop_count-- == 0) { + /* Prevent an endless loop. */ + logout("loop in %s:%u\n", __FILE__, __LINE__); + break; + } + s->cu_offset = s->tx.link; TRACE(OTHER, logout("val=(cu start), status=0x%04x, command=0x%04x, link=0x%08x\n", |