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SubjectRe: [PATCH v2 4/4] fs/pstore: fs/squashfs: Change usage of LZ4 to comply with new LZ4 module version
On Sat, Jan 7, 2017 at 8:55 AM, Sven Schmidt
<4sschmid@informatik.uni-hamburg.de> wrote:
> This patch updates fs/pstore and fs/squashfs to use the updated functions from
> the new LZ4 module.
>
> Signed-off-by: Sven Schmidt <4sschmid@informatik.uni-hamburg.de>
> ---
> fs/pstore/platform.c | 14 ++++++++------
> fs/squashfs/lz4_wrapper.c | 12 ++++++------
> 2 files changed, 14 insertions(+), 12 deletions(-)
>
> diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c
> index 729677e..a0d8ca8 100644
> --- a/fs/pstore/platform.c
> +++ b/fs/pstore/platform.c
> @@ -342,31 +342,33 @@ static int compress_lz4(const void *in, void *out, size_t inlen, size_t outlen)
> {
> int ret;
>
> - ret = lz4_compress(in, inlen, out, &outlen, workspace);
> + ret = LZ4_compress_default(in, out, inlen, outlen, workspace);
> if (ret) {
> + // ret is 0 means an error occured

If that's true, then shouldn't the "if" logic be changed? Also, here
and in all following comments are C++ style instead of kernel C-style.
This should be "/* ret == 0 means an error occured */", though really,
that should be obvious from the code and the comment isn't really
needed.

> pr_err("lz4_compress error, ret = %d!\n", ret);

If it's always going to be zero here, is there a better place to get
details on why it failed?

> return -EIO;
> }
>
> - return outlen;
> + return ret;
> }
>
> static int decompress_lz4(void *in, void *out, size_t inlen, size_t outlen)
> {
> int ret;
>
> - ret = lz4_decompress_unknownoutputsize(in, inlen, out, &outlen);
> - if (ret) {
> + ret = LZ4_decompress_safe(in, out, inlen, outlen);
> + if (ret < 0) {
> + // return value is < 0 in case of error
> pr_err("lz4_decompress error, ret = %d!\n", ret);
> return -EIO;
> }
>
> - return outlen;
> + return ret;
> }
>
> static void allocate_lz4(void)
> {
> - big_oops_buf_sz = lz4_compressbound(psinfo->bufsize);
> + big_oops_buf_sz = LZ4_compressBound(psinfo->bufsize);
> big_oops_buf = kmalloc(big_oops_buf_sz, GFP_KERNEL);
> if (big_oops_buf) {
> workspace = kmalloc(LZ4_MEM_COMPRESS, GFP_KERNEL);
> diff --git a/fs/squashfs/lz4_wrapper.c b/fs/squashfs/lz4_wrapper.c
> index ff4468b..a512399 100644
> --- a/fs/squashfs/lz4_wrapper.c
> +++ b/fs/squashfs/lz4_wrapper.c
> @@ -97,7 +97,6 @@ static int lz4_uncompress(struct squashfs_sb_info *msblk, void *strm,
> struct squashfs_lz4 *stream = strm;
> void *buff = stream->input, *data;
> int avail, i, bytes = length, res;
> - size_t dest_len = output->length;
>
> for (i = 0; i < b; i++) {
> avail = min(bytes, msblk->devblksize - offset);
> @@ -108,12 +107,13 @@ static int lz4_uncompress(struct squashfs_sb_info *msblk, void *strm,
> put_bh(bh[i]);
> }
>
> - res = lz4_decompress_unknownoutputsize(stream->input, length,
> - stream->output, &dest_len);
> - if (res)
> + res = LZ4_decompress_safe(stream->input, stream->output, length, output->length);
> + if (res < 0) {
> + // res of less than 0 means an error occured
> return -EIO;
> + }
>
> - bytes = dest_len;
> + bytes = res;
> data = squashfs_first_page(output);
> buff = stream->output;
> while (data) {
> @@ -128,7 +128,7 @@ static int lz4_uncompress(struct squashfs_sb_info *msblk, void *strm,
> }
> squashfs_finish_page(output);
>
> - return dest_len;
> + return res;
> }
>
> const struct squashfs_decompressor squashfs_lz4_comp_ops = {
> --
> 2.1.4
>

-Kees

--
Kees Cook
Nexus Security

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