Messages in this thread Patch in this message | | | Date | Sat, 03 Jun 2006 19:30:10 -0400 | From | Florin Malita <> | Subject | Re: [PATCH] ocfs2: dereference before NULL check in ocfs2_direct_IO_get_blocks() |
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Alexey Dobriyan wrote: > AFAICS, the patch is BS, as usual with this type of patches. > You missed the full purpose: the patch makes a function consistent about its own assumptions (but leaves them in place since they're on the better-safe-than-sorry side). It addresses assumptions inconsistency (confusing for both human readers and static analysis tools) just as much as it addresses a possible bug. Regardless of whether "inode" & "bh_result" can be NULL, I don't think the following is OK (coding-wise):
unsigned long max_blocks = bh_result->b_size >> inode->i_blkbits;
if (!inode || !bh_result) { mlog(ML_ERROR, "inode or bh_result is null\n"); return -EIO; }
> Can "inode" and "bh_result" be NULL here? I bet they can't Great, then the NULL branch is dead code and we can fix consistency differently:
Signed-off-by: Florin Malita <fmalita@gmail.com> ---
fs/ocfs2/aops.c | 9 +-------- 1 file changed, 1 insertion(+), 8 deletions(-)
diff --git a/fs/ocfs2/aops.c b/fs/ocfs2/aops.c index 47152bf..370c241 100644 --- a/fs/ocfs2/aops.c +++ b/fs/ocfs2/aops.c @@ -558,16 +558,9 @@ static int ocfs2_direct_IO_get_blocks(st u64 vbo_max; /* file offset, max_blocks from iblock */ u64 p_blkno; int contig_blocks; - unsigned char blocksize_bits; + unsigned char blocksize_bits = inode->i_sb->s_blocksize_bits; unsigned long max_blocks = bh_result->b_size >> inode->i_blkbits; - if (!inode || !bh_result) { - mlog(ML_ERROR, "inode or bh_result is null\n"); - return -EIO; - } - - blocksize_bits = inode->i_sb->s_blocksize_bits; - /* This function won't even be called if the request isn't all * nicely aligned and of the right size, so there's no need * for us to check any of that. */
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