[PATCH 7.1 050/228] powerpc/pseries: lparcfg - fix kbuf[] underflow

Greg Kroah-Hartman <[email protected]>
Newsgroups dev.linux.lists.patches,org.kernel.vger.stable
Message-ID <[email protected]>
7.1-stable review patch.  If anyone has any objections, please let me know.

------------------

From: George Wilson <[email protected]>

commit fb442a6673ff1046bf67754957d95880fdb394b5 upstream.

In lparcfg_write(), a count of 0 results in kbuf[] being indexed at -1.
Check for count == 0 in the existing check for count > sizeof(kbuf) and
return -EINVAL if true.

Fixes: 74422e2b1939 ("powerpc/pseries: Remove VLA from lparcfg_write()")
Acked-by: Nayna Jain <[email protected]>
Tested-by: R Nageswara Sastry <[email protected]>
Cc: [email protected] # 4.20
Signed-off-by: George Wilson <[email protected]>
Signed-off-by: Madhavan Srinivasan <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
 arch/powerpc/platforms/pseries/lparcfg.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/powerpc/platforms/pseries/lparcfg.c
+++ b/arch/powerpc/platforms/pseries/lparcfg.c
@@ -697,7 +697,7 @@ static ssize_t lparcfg_write(struct file
 	if (!firmware_has_feature(FW_FEATURE_SPLPAR))
 		return -EINVAL;
 
-	if (count > sizeof(kbuf))
+	if (count == 0 || count > sizeof(kbuf))
 		return -EINVAL;
 
 	if (copy_from_user(kbuf, buf, count))
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