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Subject[PATCH 4.19 369/639] kdb: do a sanity check on the cpu in kdb_per_cpu()
Date
From: Dan Carpenter <dan.carpenter@oracle.com>

[ 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: 5d5314d6795f ("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>
---
kernel/debug/kdb/kdb_main.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/debug/kdb/kdb_main.c b/kernel/debug/kdb/kdb_main.c
index f338d23b112b5..dc6bf35e78840 100644
--- a/kernel/debug/kdb/kdb_main.c
+++ b/kernel/debug/kdb/kdb_main.c
@@ -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;
}
--
2.20.1


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