[PATCH] net/ixgbe: fix flow control frame byte adjustment

[Bruce Richardson]

On Mon, May 04, 2026 at 05:55:02PM +0300, Daniil Iskhakov wrote:
> LXONTXC and LXOFFTXC are 32-bit counters for transmitted XON and
> XOFF packets. ixgbe_read_stats_registers() sums their deltas and uses
> the result to adjust the transmitted byte counters by the minimum
> Ethernet frame length.
> 
> The sum is currently computed as:
> 
> 	total = lxon + lxoff
> 
> Since both operands are 32-bit, the addition is performed in 32 bits
> and may wrap before the result is stored in total. The wrapped value is
> then used in the byte adjustment, which may make the software byte
> counters incorrect.
> 
> Make total 64-bit and cast lxon before the addition so the XON/XOFF
> packet sum and the following byte adjustment are computed without
> 32-bit overflow.
> 
> Found by Linux Verification Center (linuxtesting.org) with SVACE.
> 
> Fixes: af75078fece3 ("first public release")
> Cc: stable at dpdk.org
> 
> Signed-off-by: Daniil Iskhakov <dish at amicon.ru>
Acked-by: Bruce Richardson <bruce.richardson at intel.com>