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kdb: do a sanity check on the cpu in kdb_per_cpu()

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[ Upstream commit b586627e10f57ee3aa8f0cfab0d6f7dc4ae63760 ]

The "whichcpu" comes from argv[3].  The cpu_online() macro looks up the
cpu in a bitmap of online cpus, but if the value is too high then it
could read beyond the end of the bitmap and possibly Oops.

Fixes: 5d5314d679 ("kdb: core for kgdb back end (1 of 2)")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Dan Carpenter 2019-05-06 15:50:18 +03:00 • committed by Greg Kroah-Hartman
parent 69ca8d1b93
commit 9245e019e5
1 changed files with 1 additions and 1 deletions
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2
kernel/debug/kdb/kdb_main.c
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@ -2604,7 +2604,7 @@ static int kdb_per_cpu(int argc, const char **argv)
diag = kdbgetularg(argv[3], &whichcpu);
if (diag)
return diag;
if (!cpu_online(whichcpu)) {
if (whichcpu >= nr_cpu_ids || !cpu_online(whichcpu)) {
kdb_printf("cpu %ld is not online\n", whichcpu);
return KDB_BADCPUNUM;
}