Affected: Linux

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

scsi: qla2xxx: Zero SFP DMA buffer in FRU/I2C bsg handlers

The FRU and I2C bsg handlers stage their transfer in a DMA_POOL_SIZE (256-byte) bounce buffer obtained from dma_pool_alloc(), which does not zero the allocation. They initialize only a few leading bytes before handing the buffer to qla2x00_write_sfp().

qla2x00_write_sfp() can override the transfer length with a user-supplied value:

if (len == 1) opt |= BIT_0; if (opt & BIT_0) len = *sfp;

*sfp is the first byte of the (user-controlled) payload, so len can grow up to 255. The device then DMA-reads len bytes from the 256-byte pool buffer. Since only a small prefix was written (e.g. MAX_FRU_SIZE == 36 bytes for a FRU version, one byte for a FRU status register), the hardware reads past the initialized region and writes up to ~219 bytes of stale DMA-pool heap memory to the device flash.

Allocate the buffer with dma_pool_zalloc() in all five FRU/I2C handlers so any bytes beyond the initialized data are zero rather than stale heap contents.