Thread (16 messages) 16 messages, 5 authors, 2017-01-10

Re: [PATCH v2 4/4] fs/pstore: fs/squashfs: Change usage of LZ4 to comply with new LZ4 module version

From: Kees Cook <hidden>
Date: 2017-01-07 21:33:45
Also in: lkml

On Sat, Jan 7, 2017 at 8:55 AM, Sven Schmidt
[off-list ref] wrote:
quoted hunk ↗ jump to hunk
This patch updates fs/pstore and fs/squashfs to use the updated functions from
the new LZ4 module.

Signed-off-by: Sven Schmidt <redacted>
---
 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?
quoted hunk ↗ jump to hunk
                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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