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authorPhillip Lougher <phillip@lougher.demon.co.uk>2011-01-25 15:07:34 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2011-01-26 10:50:05 +1000
commit3689456b4bd36027022b3215eb2acba51cd0e6b5 (patch)
tree8233856d31d744feacf6d91b0fb7dbe7fbcf2803
parentac15ee691fe84cb46cbd2497ddcb10e246f7ee47 (diff)
downloadlinux-linaro-android-3689456b4bd36027022b3215eb2acba51cd0e6b5.tar.gz
squashfs: fix use of uninitialised variable in zlib & xz decompressors
Fix potential use of uninitialised variable caused by recent decompressor code optimisations. In zlib_uncompress (zlib_wrapper.c) we have int zlib_err, zlib_init = 0; ... do { ... if (avail == 0) { offset = 0; put_bh(bh[k++]); continue; } ... zlib_err = zlib_inflate(stream, Z_SYNC_FLUSH); ... } while (zlib_err == Z_OK); If continue is executed (avail == 0) then the while condition will be evaluated testing zlib_err, which is uninitialised first time around the loop. Fix this by getting rid of the 'if (avail == 0)' condition test, this edge condition should not be being handled in the decompressor code, and instead handle it generically in the caller code. Similarly for xz_wrapper.c. Incidentally, on most architectures (bar Mips and Parisc), no uninitialised variable warning is generated by gcc, this is because the while condition test on continue is optimised out and not performed (when executing continue zlib_err has not been changed since entering the loop, and logically if the while condition was true previously, then it's still true). Signed-off-by: Phillip Lougher <phillip@lougher.demon.co.uk> Reported-by: Jesper Juhl <jj@chaosbits.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--fs/squashfs/block.c8
-rw-r--r--fs/squashfs/xz_wrapper.c6
-rw-r--r--fs/squashfs/zlib_wrapper.c6
3 files changed, 8 insertions, 12 deletions
diff --git a/fs/squashfs/block.c b/fs/squashfs/block.c
index 2fb2882f0fa..8ab48bc2fa7 100644
--- a/fs/squashfs/block.c
+++ b/fs/squashfs/block.c
@@ -63,6 +63,14 @@ static struct buffer_head *get_block_length(struct super_block *sb,
*length = (unsigned char) bh->b_data[*offset] |
(unsigned char) bh->b_data[*offset + 1] << 8;
*offset += 2;
+
+ if (*offset == msblk->devblksize) {
+ put_bh(bh);
+ bh = sb_bread(sb, ++(*cur_index));
+ if (bh == NULL)
+ return NULL;
+ *offset = 0;
+ }
}
return bh;
diff --git a/fs/squashfs/xz_wrapper.c b/fs/squashfs/xz_wrapper.c
index 856756ca5ee..c4eb4001825 100644
--- a/fs/squashfs/xz_wrapper.c
+++ b/fs/squashfs/xz_wrapper.c
@@ -95,12 +95,6 @@ static int squashfs_xz_uncompress(struct squashfs_sb_info *msblk, void **buffer,
if (!buffer_uptodate(bh[k]))
goto release_mutex;
- if (avail == 0) {
- offset = 0;
- put_bh(bh[k++]);
- continue;
- }
-
stream->buf.in = bh[k]->b_data + offset;
stream->buf.in_size = avail;
stream->buf.in_pos = 0;
diff --git a/fs/squashfs/zlib_wrapper.c b/fs/squashfs/zlib_wrapper.c
index 818a5e063fa..4661ae2b1ce 100644
--- a/fs/squashfs/zlib_wrapper.c
+++ b/fs/squashfs/zlib_wrapper.c
@@ -82,12 +82,6 @@ static int zlib_uncompress(struct squashfs_sb_info *msblk, void **buffer,
if (!buffer_uptodate(bh[k]))
goto release_mutex;
- if (avail == 0) {
- offset = 0;
- put_bh(bh[k++]);
- continue;
- }
-
stream->next_in = bh[k]->b_data + offset;
stream->avail_in = avail;
offset = 0;