powerpc/xmon: Check cpu id in commands "c#", "dp#" and "dx#"

[ Upstream commit 8873aab8646194a4446117bb617cc71bddda2dee ]

All these commands end up peeking into the PACA using the user
originated cpu id as an index. Check the cpu id is valid in order
to prevent xmon to crash. Instead of printing an error, this follows
the same behavior as the "lp s #" command : ignore the buggy cpu id
parameter and fall back to the #-less version of the command.

Signed-off-by: Greg Kurz <groug@kaod.org>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/161531347060.252863.10490063933688958044.stgit@bahia.lan
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/arch/powerpc/xmon/xmon.c b/arch/powerpc/xmon/xmon.c
index 6d130c89fbd856fe0d23a4645657d4aeccc5c91a..5991fd06b6525835ce668edddac0926b10a16316 100644 (file)
--- a/arch/powerpc/xmon/xmon.c
+++ b/arch/powerpc/xmon/xmon.c
@@ -1214,7 +1214,7 @@ static int cpu_cmd(void)
        unsigned long cpu, first_cpu, last_cpu;
        int timeout;
 
-       if (!scanhex(&cpu)) {
+       if (!scanhex(&cpu) || cpu >= num_possible_cpus()) {
                /* print cpus waiting or in xmon */
                printf("cpus stopped:");
                last_cpu = first_cpu = NR_CPUS;
@@ -2571,7 +2571,7 @@ static void dump_pacas(void)
 
        termch = c;     /* Put c back, it wasn't 'a' */
 
-       if (scanhex(&num))
+       if (scanhex(&num) && num < num_possible_cpus())
                dump_one_paca(num);
        else
                dump_one_paca(xmon_owner);
@@ -2668,7 +2668,7 @@ static void dump_xives(void)
 
        termch = c;     /* Put c back, it wasn't 'a' */
 
-       if (scanhex(&num))
+       if (scanhex(&num) && num < num_possible_cpus())
                dump_one_xive(num);
        else
                dump_one_xive(xmon_owner);