[Xen-devel] [PATCH 2/7] tools/misc: fix hypothetical buffer overflow in xen-lowmemd

[Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>]

gcc-8 complains:

    xen-lowmemd.c: In function 'handle_low_mem':
    xen-lowmemd.c:80:55: error: '%s' directive output may be truncated writing 
up to 511 bytes into a region of size 489 [-Werror=format-truncation=]
             snprintf(error, BUFSZ,"Failed to write target %s to xenstore", 
data);
                                                           ^~               ~~~~
    xen-lowmemd.c:80:9: note: 'snprintf' output between 36 and 547 bytes into a 
destination of size 512
             snprintf(error, BUFSZ,"Failed to write target %s to xenstore", 
data);
             
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

In practice it wouldn't happen, because 'data' contains string
representation of 64-bit unsigned number (20 characters at most).
But place a limit to mute gcc warning.

Signed-off-by: Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>
---
 tools/misc/xen-lowmemd.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/misc/xen-lowmemd.c b/tools/misc/xen-lowmemd.c
index 865a54c..79ad34c 100644
--- a/tools/misc/xen-lowmemd.c
+++ b/tools/misc/xen-lowmemd.c
@@ -77,7 +77,7 @@ void handle_low_mem(void)
     if (!xs_write(xs_handle, XBT_NULL, 
             "/local/domain/0/memory/target", data, strlen(data)))
     {
-        snprintf(error, BUFSZ,"Failed to write target %s to xenstore", data);
+        snprintf(error, BUFSZ,"Failed to write target %.24s to xenstore", 
data);
         perror(error);
     }
 }
-- 
git-series 0.9.1

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