[Qemu-devel] [PATCHv3 03/20] block: avoid buffer overrun by using pstrcpy, not strncpy

[Jim Meyering]

From: Jim Meyering <address@hidden>

Also, use PATH_MAX, rather than the arbitrary 1024.
Using PATH_MAX is more consistent with other filename-related
variables in this file, like backing_filename and tmp_filename.

Acked-by: Kevin Wolf <address@hidden>
Signed-off-by: Jim Meyering <address@hidden>
---
 block.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/block.c b/block.c
index 751ebdc..b62432c 100644
--- a/block.c
+++ b/block.c
@@ -1503,7 +1503,7 @@ int bdrv_commit(BlockDriverState *bs)
     int n, ro, open_flags;
     int ret = 0;
     uint8_t *buf;
-    char filename[1024];
+    char filename[PATH_MAX];

     if (!drv)
         return -ENOMEDIUM;
@@ -1517,7 +1517,8 @@ int bdrv_commit(BlockDriverState *bs)
     }

     ro = bs->backing_hd->read_only;
-    strncpy(filename, bs->backing_hd->filename, sizeof(filename));
+    /* Use pstrcpy (not strncpy): filename must be NUL-terminated. */
+    pstrcpy(filename, sizeof(filename), bs->backing_hd->filename);
     open_flags =  bs->backing_hd->open_flags;

     if (ro) {
-- 
1.8.0.rc0.18.gf84667d