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| author | Stephen Longfield <slongfield@google.com> | 2023-02-07 09:02:04 +0100 |
|---|---|---|
| committer | Cédric Le Goater <clg@kaod.org> | 2023-02-07 09:02:04 +0100 |
| commit | 036e98e5c2b4e25c8d6ccbddb85c7ab05a753f6a (patch) | |
| tree | efc020727039a0c6fa10106d401d929b8b08e37f | |
| parent | 479365979bdc2fc4f8d2375085c980fe3f520c39 (diff) | |
| download | focaccia-qemu-036e98e5c2b4e25c8d6ccbddb85c7ab05a753f6a.tar.gz focaccia-qemu-036e98e5c2b4e25c8d6ccbddb85c7ab05a753f6a.zip | |
hw/net: Fix read of uninitialized memory in ftgmac100
With the `size += 4` before the call to `crc32`, the CRC calculation would overrun the buffer. Size is used in the while loop starting on line 1009 to determine how much data to write back, with the last four bytes coming from `crc_ptr`, so do need to increase it, but should do this after the computation. I'm unsure why this use of uninitialized memory in the CRC doesn't result in CRC errors, but it seems clear to me that it should not be included in the calculation. Signed-off-by: Stephen Longfield <slongfield@google.com> Reviewed-by: Hao Wu <wuhaotsh@google.com> Reviewed-by: Joel Stanley <joel@jms.id.au> Message-Id: <20221220221437.3303721-1-slongfield@google.com> Signed-off-by: Cédric Le Goater <clg@kaod.org>
| -rw-r--r-- | hw/net/ftgmac100.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/hw/net/ftgmac100.c b/hw/net/ftgmac100.c index 83ef0a783e..d3bf14be53 100644 --- a/hw/net/ftgmac100.c +++ b/hw/net/ftgmac100.c @@ -980,9 +980,9 @@ static ssize_t ftgmac100_receive(NetClientState *nc, const uint8_t *buf, return size; } - /* 4 bytes for the CRC. */ - size += 4; crc = cpu_to_be32(crc32(~0, buf, size)); + /* Increase size by 4, loop below reads the last 4 bytes from crc_ptr. */ + size += 4; crc_ptr = (uint8_t *) &crc; /* Huge frames are truncated. */ |