On 8/20/14, 10:35 PM, Gui Hecheng wrote:
> A memory problem reported by valgrind as follows:
> === Syscall param pwrite64(buf) points to uninitialised byte(s)
> When running:
> # valgrind --leak-check=yes btrfs restore /dev/sda9 /mnt/backup
>
> Because the output buf size is alloced with malloc, but the length of
> output data is shorter than the sizeof(buf), so valgrind report
> uninitialised byte(s).
> We could use calloc to repalce malloc and clear this WARNING away.
>
> Reported-by: Marc Dietrich <marvin24@xxxxxx>
> Signed-off-by: Gui Hecheng <guihc.fnst@xxxxxxxxxxxxxx>
Sorry for the noise in reply to this, I think the patch itself
is fine. It would have clarified things to the reviewer, though,
if you had added more detail to the commit log, such as:
> If a btrfs-restore process encounters corruption and fails
> to properly decompress all data, some parts of the output
> buffer may not be initialized. This was reported by valgrind as
> follows:
> === Syscall param pwrite64(buf) points to uninitialised byte(s)
> When running:
> # valgrind --leak-check=yes btrfs restore /dev/sda9 /mnt/backup
>
> Because the output buf size is alloced with malloc, but the length of
> output data is shorter than the sizeof(buf), so valgrind reports
> uninitialised byte(s).
>
> We could use calloc to replace malloc to ensure that all written
> bytes are initialized.
Anyway:
Reviewed-by: Eric Sandeen <sandeen@xxxxxxxxxx>
Thanks,
-Eric
> ---
> cmds-restore.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/cmds-restore.c b/cmds-restore.c
> index cbda6bb..bb72311 100644
> --- a/cmds-restore.c
> +++ b/cmds-restore.c
> @@ -251,7 +251,7 @@ static int copy_one_inline(int fd, struct btrfs_path *path, u64 pos)
> }
>
> ram_size = btrfs_file_extent_ram_bytes(leaf, fi);
> - outbuf = malloc(ram_size);
> + outbuf = calloc(1, ram_size);
> if (!outbuf) {
> fprintf(stderr, "No memory\n");
> return -ENOMEM;
> @@ -320,7 +320,7 @@ static int copy_one_extent(struct btrfs_root *root, int fd,
> }
>
> if (compress != BTRFS_COMPRESS_NONE) {
> - outbuf = malloc(ram_size);
> + outbuf = calloc(1, ram_size);
> if (!outbuf) {
> fprintf(stderr, "No memory\n");
> free(inbuf);
>
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