[PATCH 5/7] Handle snprintf calulation more graceful in v9fs

[Eric Sesterhenn]

snprintf might return a value bigger than limit when the string gets
truncated, which would cause the return value to become bogus.

Signed-off-by: Eric Sesterhenn <eric.sesterhenn@x41-dsec.>
---
 fs/9p/v9fs.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/fs/9p/v9fs.c b/fs/9p/v9fs.c
index 8fb89ddc6cc7..9e7cefc26ad9 100644
--- a/fs/9p/v9fs.c
+++ b/fs/9p/v9fs.c
@@ -552,6 +552,10 @@ static ssize_t caches_show(struct kobject *kobj,
        list_for_each_entry(v9ses, &v9fs_sessionlist, slist) {
                if (v9ses->cachetag) {
                        n = snprintf(buf, limit, "%s\n", v9ses->cachetag);
+                       if (n > limit) {
+                               count = PAGE_SIZE;
+                               break;
+                       }
                        if (n < 0) {
                                count = n;
                                break;

-- 
Eric Sesterhenn (Principal Security Consultant)
X41 D-SEC GmbH, Dennewartstr. 25-27, D-52068 Aachen
T: +49 241 9809418-0, Fax: -9
Unternehmenssitz: Aachen, Amtsgericht Aachen: HRB19989
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