Re: [PATCH] IB/ucm: Fix Spectre v1 vulnerability

From: Doug Ledford
Date: Tue Oct 16 2018 - 12:49:30 EST


On Tue, 2018-10-16 at 16:32 +0200, Gustavo A. R. Silva wrote:
> 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@xxxxxxxxxxxxxxx
> Signed-off-by: Gustavo A. R. Silva <gustavo@xxxxxxxxxxxxxx>

Thanks, applied to for-rc.

--
Doug Ledford <dledford@xxxxxxxxxx>
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Key fingerprint = AE6B 1BDA 122B 23B4 265B 1274 B826 A333 0E57 2FDD

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