* [patch] hfs: fix hfs_readdir()
@ 2016-01-26 9:26 Dan Carpenter
2016-01-26 18:18 ` Viacheslav Dubeyko
0 siblings, 1 reply; 6+ messages in thread
From: Dan Carpenter @ 2016-01-26 9:26 UTC (permalink / raw)
To: Chengyu Song
Cc: Andrew Morton, David Howells, Al Viro, linux-fsdevel,
linux-kernel, kernel-janitors
I was looking through static analysis warnings and we seem to be copying
garbage into &rd->key. This goes back to before the start of git...
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
---
Not tested. Please review carefully.
diff --git a/fs/hfs/dir.c b/fs/hfs/dir.c
index 70788e0..66485d7 100644
--- a/fs/hfs/dir.c
+++ b/fs/hfs/dir.c
@@ -163,7 +163,7 @@ static int hfs_readdir(struct file *file, struct dir_context *ctx)
rd->file = file;
list_add(&rd->list, &HFS_I(inode)->open_dir_list);
}
- memcpy(&rd->key, &fd.key, sizeof(struct hfs_cat_key));
+ memcpy(&rd->key, &fd.key->cat, sizeof(struct hfs_cat_key));
out:
hfs_find_exit(&fd);
return err;
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [patch] hfs: fix hfs_readdir()
2016-01-26 9:26 [patch] hfs: fix hfs_readdir() Dan Carpenter
@ 2016-01-26 18:18 ` Viacheslav Dubeyko
2016-01-26 19:18 ` Dan Carpenter
0 siblings, 1 reply; 6+ messages in thread
From: Viacheslav Dubeyko @ 2016-01-26 18:18 UTC (permalink / raw)
To: Dan Carpenter
Cc: Chengyu Song, Andrew Morton, David Howells, Al Viro,
linux-fsdevel, linux-kernel, kernel-janitors
On Tue, 2016-01-26 at 12:26 +0300, Dan Carpenter wrote:
> I was looking through static analysis warnings and we seem to be copying
> garbage into &rd->key. This goes back to before the start of git...
>
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> ---
> Not tested. Please review carefully.
>
> diff --git a/fs/hfs/dir.c b/fs/hfs/dir.c
> index 70788e0..66485d7 100644
> --- a/fs/hfs/dir.c
> +++ b/fs/hfs/dir.c
> @@ -163,7 +163,7 @@ static int hfs_readdir(struct file *file, struct dir_context *ctx)
> rd->file = file;
> list_add(&rd->list, &HFS_I(inode)->open_dir_list);
> }
> - memcpy(&rd->key, &fd.key, sizeof(struct hfs_cat_key));
> + memcpy(&rd->key, &fd.key->cat, sizeof(struct hfs_cat_key));
The field "key" is union:
164 typedef union hfs_btree_key {
165 u8 key_len; /* number of bytes in the key */
166 struct hfs_cat_key cat;
167 struct hfs_ext_key ext;
168 } hfs_btree_key;
The struct hfs_cat_key is the biggest item. So, size of this structure
is dominating in the union:
157 struct hfs_ext_key {
158 u8 key_len; /* number of bytes in the key */
159 u8 FkType; /* HFS_FK_{DATA,RSRC} */
160 __be32 FNum; /* The File ID of the file */
161 __be16 FABN; /* allocation blocks number*/
162 } __packed;
149 struct hfs_cat_key {
150 u8 key_len; /* number of bytes in the key */
151 u8 reserved; /* padding */
152 __be32 ParID; /* CNID of the parent dir */
153 struct hfs_name CName; /* The filename of the entry */
154 } __packed;
because:
27 #define HFS_NAMELEN 31 /* maximum length of an HFS filename */
87 struct hfs_name {
88 u8 len;
89 u8 name[HFS_NAMELEN];
90 } __packed;
If we are using sizeof(struct hfs_cat_key) then it looks like that we
could potentially miss one byte of the union during catalog key copying.
But if we will copy struct hfs_ext_key then we will copy some amount of
"garbage" anyway. So, I don't think that it's good fix of the issue.
What do you think?
Another worry could be the "search_key" field of the struct
hfs_find_data.
Thanks,
Vyacheslav Dubeyko.
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [patch] hfs: fix hfs_readdir()
2016-01-26 18:18 ` Viacheslav Dubeyko
@ 2016-01-26 19:18 ` Dan Carpenter
2016-01-26 21:54 ` Viacheslav Dubeyko
0 siblings, 1 reply; 6+ messages in thread
From: Dan Carpenter @ 2016-01-26 19:18 UTC (permalink / raw)
To: Viacheslav Dubeyko
Cc: Chengyu Song, Andrew Morton, David Howells, Al Viro,
linux-fsdevel, linux-kernel, kernel-janitors
Hm, I completely didn't see that it was a union instead of a struct. I
still think my fix is actually correct though. Now that you point out
the union, I see that my change is equivalent to just removing the '&'
char.
- memcpy(&rd->key, &fd.key, sizeof(struct hfs_cat_key));
+ memcpy(&rd->key, fd.key, sizeof(struct hfs_cat_key));
We don't want to copy sizeof(*fd.key) because that would write past the
end of the destination struct.
On Tue, Jan 26, 2016 at 10:18:56AM -0800, Viacheslav Dubeyko wrote:
> Another worry could be the "search_key" field of the struct
> hfs_find_data.
I don't understand what you mean here.
regards,
dan carpenter
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [patch] hfs: fix hfs_readdir()
2016-01-26 19:18 ` Dan Carpenter
@ 2016-01-26 21:54 ` Viacheslav Dubeyko
2017-01-16 14:22 ` Dan Carpenter
0 siblings, 1 reply; 6+ messages in thread
From: Viacheslav Dubeyko @ 2016-01-26 21:54 UTC (permalink / raw)
To: Dan Carpenter
Cc: Chengyu Song, Andrew Morton, David Howells, Al Viro,
linux-fsdevel, linux-kernel, kernel-janitors
On Tue, 2016-01-26 at 22:18 +0300, Dan Carpenter wrote:
> Hm, I completely didn't see that it was a union instead of a struct. I
> still think my fix is actually correct though. Now that you point out
> the union, I see that my change is equivalent to just removing the '&'
> char.
>
> - memcpy(&rd->key, &fd.key, sizeof(struct hfs_cat_key));
> + memcpy(&rd->key, fd.key, sizeof(struct hfs_cat_key));
>
Yeahh, it looks correct right now. The rd is the pointer that includes
struct hfs_cat_key object. So, we need to use &rd->key. But on another
side we have struct hfs_find_data object on the stack. And this object
includes the pointer on union btree_key. We want to copy struct
hfs_cat_key object and we should use sizeof(struct hfs_cat_key).
> We don't want to copy sizeof(*fd.key) because that would write past the
> end of the destination struct.
>
> On Tue, Jan 26, 2016 at 10:18:56AM -0800, Viacheslav Dubeyko wrote:
> > Another worry could be the "search_key" field of the struct
> > hfs_find_data.
>
> I don't understand what you mean here.
>
I mean here that we could have another incorrect copy operations for
"search_key" field. That's all.
Thanks,
Vyacheslav Dubeyko.
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [patch] hfs: fix hfs_readdir()
2016-01-26 21:54 ` Viacheslav Dubeyko
@ 2017-01-16 14:22 ` Dan Carpenter
2017-01-16 22:34 ` Viacheslav Dubeyko
0 siblings, 1 reply; 6+ messages in thread
From: Dan Carpenter @ 2017-01-16 14:22 UTC (permalink / raw)
To: Viacheslav Dubeyko
Cc: Chengyu Song, Andrew Morton, David Howells, Al Viro,
linux-fsdevel, linux-kernel, kernel-janitors
I was reviewing old warnings and I stumbled across this one again.
Although I wrote that &fd.key->cat and "fd.key" are equivalent, I feel
that actually we should be doing the former. fd.key is a union but we
want the ->cat member of the union.
On Tue, Jan 26, 2016 at 01:54:06PM -0800, Viacheslav Dubeyko wrote:
> On Tue, 2016-01-26 at 22:18 +0300, Dan Carpenter wrote:
> > Hm, I completely didn't see that it was a union instead of a struct. I
> > still think my fix is actually correct though. Now that you point out
> > the union, I see that my change is equivalent to just removing the '&'
> > char.
> >
> > - memcpy(&rd->key, &fd.key, sizeof(struct hfs_cat_key));
> > + memcpy(&rd->key, fd.key, sizeof(struct hfs_cat_key));
> >
>
> Yeahh, it looks correct right now. The rd is the pointer that includes
> struct hfs_cat_key object. So, we need to use &rd->key. But on another
> side we have struct hfs_find_data object on the stack. And this object
> includes the pointer on union btree_key. We want to copy struct
> hfs_cat_key object and we should use sizeof(struct hfs_cat_key).
I've read this paragraph several times now and I think you are saying
that the patch is correct.
>
> > We don't want to copy sizeof(*fd.key) because that would write past the
> > end of the destination struct.
> >
> > On Tue, Jan 26, 2016 at 10:18:56AM -0800, Viacheslav Dubeyko wrote:
> > > Another worry could be the "search_key" field of the struct
> > > hfs_find_data.
> >
> > I don't understand what you mean here.
> >
>
> I mean here that we could have another incorrect copy operations for
> "search_key" field. That's all.
I don't see the bugs you are saying might exist... ;)
regards,
dan carpenter
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [patch] hfs: fix hfs_readdir()
2017-01-16 14:22 ` Dan Carpenter
@ 2017-01-16 22:34 ` Viacheslav Dubeyko
0 siblings, 0 replies; 6+ messages in thread
From: Viacheslav Dubeyko @ 2017-01-16 22:34 UTC (permalink / raw)
To: Dan Carpenter
Cc: Chengyu Song, Andrew Morton, David Howells, Al Viro,
linux-fsdevel, linux-kernel, kernel-janitors
On Mon, 2017-01-16 at 17:22 +0300, Dan Carpenter wrote:
> I was reviewing old warnings and I stumbled across this one again.
> Although I wrote that &fd.key->cat and "fd.key" are equivalent, I
> feel
> that actually we should be doing the former. fd.key is a union but
> we
> want the ->cat member of the union.
>
> On Tue, Jan 26, 2016 at 01:54:06PM -0800, Viacheslav Dubeyko wrote:
> >
> > On Tue, 2016-01-26 at 22:18 +0300, Dan Carpenter wrote:
> > >
> > > Hm, I completely didn't see that it was a union instead of a
> > > struct. I
> > > still think my fix is actually correct though. Now that you
> > > point out
> > > the union, I see that my change is equivalent to just removing
> > > the '&'
> > > char.
> > >
> > > - memcpy(&rd->key, &fd.key, sizeof(struct hfs_cat_key));
> > > + memcpy(&rd->key, fd.key, sizeof(struct hfs_cat_key));
> > >
> > Yeahh, it looks correct right now. The rd is the pointer that
> > includes
> > struct hfs_cat_key object. So, we need to use &rd->key. But on
> > another
> > side we have struct hfs_find_data object on the stack. And this
> > object
> > includes the pointer on union btree_key. We want to copy struct
> > hfs_cat_key object and we should use sizeof(struct hfs_cat_key).
> I've read this paragraph several times now and I think you are saying
> that the patch is correct.
>
Yes, I've said that patch looks good. I think it's better to resend the
patch again.
Thanks,
Vyacheslav Dubeyko.
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2017-01-16 22:43 UTC | newest]
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2016-01-26 9:26 [patch] hfs: fix hfs_readdir() Dan Carpenter
2016-01-26 18:18 ` Viacheslav Dubeyko
2016-01-26 19:18 ` Dan Carpenter
2016-01-26 21:54 ` Viacheslav Dubeyko
2017-01-16 14:22 ` Dan Carpenter
2017-01-16 22:34 ` Viacheslav Dubeyko
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