* [PATCH] Staging: exfat: Avoid use of strcpy
@ 2019-09-11 5:57 Sandro Volery
2019-09-11 8:41 ` Dan Carpenter
0 siblings, 1 reply; 3+ messages in thread
From: Sandro Volery @ 2019-09-11 5:57 UTC (permalink / raw)
To: valdis.kletnieks, gregkh, devel, linux-kernel
Replaced strcpy with strscpy in exfat_core.c.
Signed-off-by: Sandro Volery <sandro@volery.com>
---
drivers/staging/exfat/exfat_core.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/staging/exfat/exfat_core.c b/drivers/staging/exfat/exfat_core.c
index da8c58149c35..c71b145e8a24 100644
--- a/drivers/staging/exfat/exfat_core.c
+++ b/drivers/staging/exfat/exfat_core.c
@@ -2964,7 +2964,7 @@ s32 resolve_path(struct inode *inode, char *path, struct chain_t *p_dir,
if (strlen(path) >= (MAX_NAME_LENGTH * MAX_CHARSET_SIZE))
return FFS_INVALIDPATH;
- strcpy(name_buf, path);
+ strscpy(name_buf, path, sizeof(name_buf));
nls_cstring_to_uniname(sb, p_uniname, name_buf, &lossy);
if (lossy)
--
2.23.0
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^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] Staging: exfat: Avoid use of strcpy
2019-09-11 5:57 [PATCH] Staging: exfat: Avoid use of strcpy Sandro Volery
@ 2019-09-11 8:41 ` Dan Carpenter
2019-09-11 8:56 ` Rasmus Villemoes
0 siblings, 1 reply; 3+ messages in thread
From: Dan Carpenter @ 2019-09-11 8:41 UTC (permalink / raw)
To: Sandro Volery; +Cc: devel, gregkh, valdis.kletnieks, linux-kernel
On Wed, Sep 11, 2019 at 07:57:49AM +0200, Sandro Volery wrote:
> Replaced strcpy with strscpy in exfat_core.c.
>
> Signed-off-by: Sandro Volery <sandro@volery.com>
> ---
> drivers/staging/exfat/exfat_core.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/staging/exfat/exfat_core.c b/drivers/staging/exfat/exfat_core.c
> index da8c58149c35..c71b145e8a24 100644
> --- a/drivers/staging/exfat/exfat_core.c
> +++ b/drivers/staging/exfat/exfat_core.c
> @@ -2964,7 +2964,7 @@ s32 resolve_path(struct inode *inode, char *path, struct chain_t *p_dir,
> if (strlen(path) >= (MAX_NAME_LENGTH * MAX_CHARSET_SIZE))
> return FFS_INVALIDPATH;
>
> - strcpy(name_buf, path);
> + strscpy(name_buf, path, sizeof(name_buf));
It checked strlen() earlier so we know that it can't overflow but, oh
wow, the "name_buf" is a shared buffer. wow wow wow. This seems very
racy.
regards,
dan carpenter
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* Re: [PATCH] Staging: exfat: Avoid use of strcpy
2019-09-11 8:41 ` Dan Carpenter
@ 2019-09-11 8:56 ` Rasmus Villemoes
0 siblings, 0 replies; 3+ messages in thread
From: Rasmus Villemoes @ 2019-09-11 8:56 UTC (permalink / raw)
To: Dan Carpenter, Sandro Volery
Cc: devel, gregkh, valdis.kletnieks, linux-kernel
On 11/09/2019 10.41, Dan Carpenter wrote:
> On Wed, Sep 11, 2019 at 07:57:49AM +0200, Sandro Volery wrote:
>> Replaced strcpy with strscpy in exfat_core.c.
>>
>> Signed-off-by: Sandro Volery <sandro@volery.com>
>> ---
>> drivers/staging/exfat/exfat_core.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/staging/exfat/exfat_core.c b/drivers/staging/exfat/exfat_core.c
>> index da8c58149c35..c71b145e8a24 100644
>> --- a/drivers/staging/exfat/exfat_core.c
>> +++ b/drivers/staging/exfat/exfat_core.c
>> @@ -2964,7 +2964,7 @@ s32 resolve_path(struct inode *inode, char *path, struct chain_t *p_dir,
>> if (strlen(path) >= (MAX_NAME_LENGTH * MAX_CHARSET_SIZE))
>> return FFS_INVALIDPATH;
>>
>> - strcpy(name_buf, path);
>> + strscpy(name_buf, path, sizeof(name_buf));
>
> It checked strlen() earlier so we know that it can't overflow but, oh
> wow, the "name_buf" is a shared buffer. wow wow wow. This seems very
> racy.
Yeah, and note that the callers of resolve_path do seem to take a lock,
but that's not a global lock but a per-superblock (or
per-something-else) one... Obviously exfat should not rely on such a
single static buffer, but in the meantime, perhaps one should add a
name_buf_lock (though I don't know how long name_buf is actually in use,
so that needs checking).
Apart from the broken/lack of locking, it would be better to combine the
copying and length checking into a single check - i.e. do
if (strscpy(name_buf, path, sizeof(name_buf)) < 0)
return FFS_INVALIDPATH;
That's both more efficient and fixes the open-coding of sizeof(name_buf)
that is currently used in the if().
Rasmus
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2019-09-11 5:57 [PATCH] Staging: exfat: Avoid use of strcpy Sandro Volery
2019-09-11 8:41 ` Dan Carpenter
2019-09-11 8:56 ` Rasmus Villemoes
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