Affected: Linux

In the Linux kernel, the following vulnerability has been resolved:

net: macb: fix a memory corruption in extended buffer descriptor mode

For quite some time we were chasing a bug which looked like a sudden permanent failure of networking and mmc on some of our devices. The bug was very sensitive to any software changes and even more to any kernel debug options.

Finally we got a setup where the problem was reproducible with CONFIG_DMA_API_DEBUG=y and it revealed the issue with the rx dma:

[ 16.992082] ------------[ cut here ]------------ [ 16.996779] DMA-API: macb ff0b0000.ethernet: device driver tries to free DMA memory it has not allocated [device address=0x0000000875e3e244] [size=1536 bytes] [ 17.011049] WARNING: CPU: 0 PID: 85 at kernel/dma/debug.c:1011 check_unmap+0x6a0/0x900 [ 17.018977] Modules linked in: xxxxx [ 17.038823] CPU: 0 PID: 85 Comm: irq/55-8000f000 Not tainted 5.4.0 #28 [ 17.045345] Hardware name: xxxxx [ 17.049528] pstate: 60000005 (nZCv daif -PAN -UAO) [ 17.054322] pc : check_unmap+0x6a0/0x900 [ 17.058243] lr : check_unmap+0x6a0/0x900 [ 17.062163] sp : ffffffc010003c40 [ 17.065470] x29: ffffffc010003c40 x28: 000000004000c03c [ 17.070783] x27: ffffffc010da7048 x26: ffffff8878e38800 [ 17.076095] x25: ffffff8879d22810 x24: ffffffc010003cc8 [ 17.081407] x23: 0000000000000000 x22: ffffffc010a08750 [ 17.086719] x21: ffffff8878e3c7c0 x20: ffffffc010acb000 [ 17.092032] x19: 0000000875e3e244 x18: 0000000000000010 [ 17.097343]…