linux-kernel - [PATCH V2 1/3] x86/numa_emulation: fix potential memory leak

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Date:   Tue,  2 May 2017 21:04:51 +0800
From:   Wei Yang <richard.weiyang@...il.com>
To:     kirill@...temov.name, bp@...en8.de, tglx@...utronix.de,
        mingo@...hat.com, hpa@...or.com, tj@...nel.org, rientjes@...gle.com
Cc:     linux-kernel@...r.kernel.org, Wei Yang <richard.weiyang@...il.com>
Subject: [PATCH V2 1/3] x86/numa_emulation: fix potential memory leak

numa_emulation() needs to allocate a space for phys_dist[] temporarily,
while current code may miss to release this when dfl_phys_nid ==
NUMA_NO_NODE. It is observed in code review instead of in a real case.

This patch fixes this by re-order the code path.

Signed-off-by: Wei Yang <richard.weiyang@...il.com>
Acked-by: David Rientjes <rientjes@...gle.com>
---
 arch/x86/mm/numa_emulation.c | 36 ++++++++++++++++++------------------
 1 file changed, 18 insertions(+), 18 deletions(-)

diff --git a/arch/x86/mm/numa_emulation.c b/arch/x86/mm/numa_emulation.c
index a8f90ce3dedf..eb017c816de6 100644
--- a/arch/x86/mm/numa_emulation.c
+++ b/arch/x86/mm/numa_emulation.c
@@ -353,6 +353,24 @@ void __init numa_emulation(struct numa_meminfo *numa_meminfo, int numa_dist_cnt)
 		goto no_emu;
 	}
 
+	/*
+	 * Determine the max emulated nid and the default phys nid to use
+	 * for unmapped nodes.
+	 */
+	max_emu_nid = 0;
+	dfl_phys_nid = NUMA_NO_NODE;
+	for (i = 0; i < ARRAY_SIZE(emu_nid_to_phys); i++) {
+		if (emu_nid_to_phys[i] != NUMA_NO_NODE) {
+			max_emu_nid = i;
+			if (dfl_phys_nid == NUMA_NO_NODE)
+				dfl_phys_nid = emu_nid_to_phys[i];
+		}
+	}
+	if (dfl_phys_nid == NUMA_NO_NODE) {
+		pr_warn("NUMA: Warning: can't determine default physical node, disabling emulation\n");
+		goto no_emu;
+	}
+
 	/* copy the physical distance table */
 	if (numa_dist_cnt) {
 		u64 phys;
@@ -372,24 +390,6 @@ void __init numa_emulation(struct numa_meminfo *numa_meminfo, int numa_dist_cnt)
 					node_distance(i, j);
 	}
 
-	/*
-	 * Determine the max emulated nid and the default phys nid to use
-	 * for unmapped nodes.
-	 */
-	max_emu_nid = 0;
-	dfl_phys_nid = NUMA_NO_NODE;
-	for (i = 0; i < ARRAY_SIZE(emu_nid_to_phys); i++) {
-		if (emu_nid_to_phys[i] != NUMA_NO_NODE) {
-			max_emu_nid = i;
-			if (dfl_phys_nid == NUMA_NO_NODE)
-				dfl_phys_nid = emu_nid_to_phys[i];
-		}
-	}
-	if (dfl_phys_nid == NUMA_NO_NODE) {
-		pr_warning("NUMA: Warning: can't determine default physical node, disabling emulation\n");
-		goto no_emu;
-	}
-
 	/* commit */
 	*numa_meminfo = ei;
 
-- 
2.11.0