[PATCH 1/3] fs/proc/task_mmu.c: check the return value of mpol_to_str()

[Chen Gang]

mpol_to_str() may fail, and not fill the buffer (e.g. -EINVAL), so need
check about it, or buffer may not be zero based, and next seq_printf()
will cause issue.

The failure return need after mpol_cond_put() to match get_vma_policy().


Signed-off-by: Chen Gang <gang.chen@xxxxxxxxxxx>
Cc: Cyrill Gorcunov <gorcunov@xxxxxxxxx>
---
 fs/proc/task_mmu.c |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 107d026..d87f5da 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -1376,8 +1376,10 @@ static int show_numa_map(struct seq_file *m, void *v, int is_pid)
 	walk.mm = mm;
 
 	pol = get_vma_policy(task, vma, vma->vm_start);
-	mpol_to_str(buffer, sizeof(buffer), pol);
+	n = mpol_to_str(buffer, sizeof(buffer), pol);
 	mpol_cond_put(pol);
+	if (n < 0)
+		return n;
 
 	seq_printf(m, "%08lx %s", vma->vm_start, buffer);
 
-- 
1.7.7.6
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