commit 0295e39595 upstream.
hdr.cmd can be indirectly controlled by user-space, hence leading to
a potential exploitation of the Spectre variant 1 vulnerability.
This issue was detected with the help of Smatch:
drivers/infiniband/core/ucm.c:1127 ib_ucm_write() warn: potential
spectre issue 'ucm_cmd_table' [r] (local cap)
Fix this by sanitizing hdr.cmd before using it to index
ucm_cmd_table.
Notice that given that speculation windows are large, the policy is
to kill the speculation on the first load and not worry if it can be
completed with a dependent load/store [1].
[1] https://marc.info/?l=linux-kernel&m=152449131114778&w=2
Cc: stable@vger.kernel.org
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
f0e3b74a4d