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hw/net/virtio-net.c: Don't assume IP length field is aligned

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In virtio-net.c we assume that the IP length field in the packet is
aligned, and we copy its address into a uint16_t* in the
VirtioNetRscUnit struct which we then dereference later.  This isn't
a safe assumption; it will also result in compilation failures if we
mark the ip_header struct as QEMU_PACKED because the compiler will
not let you take the address of an unaligned struct field.

Make the ip_plen field in VirtioNetRscUnit a void*, and make all the
places where we read or write through that pointer instead use some
new accessor functions read_unit_ip_len() and write_unit_ip_len()
which account for the pointer being potentially unaligned and also do
the network-byte-order conversion we were previously using htons() to
perform.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-ID: <20241114141619.806652-2-peter.maydell@linaro.org>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
This commit is contained in:
Peter Maydell 2024-11-14 14:16:18 +00:00 • committed by Philippe Mathieu-Daudé
parent 626b39006d
commit 5814c08467
2 changed files with 20 additions and 5 deletions
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2
include/hw/virtio/virtio-net.h
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@ -102,7 +102,7 @@ typedef struct VirtioNetRscStat {
/* Rsc unit general info used to checking if can coalescing */
typedef struct VirtioNetRscUnit {
void *ip; /* ip header */
uint16_t *ip_plen; /* data len pointer in ip header field */
void *ip_plen; /* pointer to unaligned uint16_t data len in ip header */
struct tcp_header *tcp; /* tcp header */
uint16_t tcp_hdrlen; /* tcp header len */
uint16_t payload; /* pure payload without virtio/eth/ip/tcp */