* [PATCH] fs/cifs: suppress a string overflow warning
@ 2018-09-03 3:15 Stephen Rothwell
2018-09-03 14:44 ` Steve French
0 siblings, 1 reply; 4+ messages in thread
From: Stephen Rothwell @ 2018-09-03 3:15 UTC (permalink / raw)
To: Steve French; +Cc: linux-cifs, samba-technical, Linux-kernel Mailing List
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A powerpc build of cifs with gcc v8.2.0 produces this warning:
fs/cifs/cifssmb.c: In function ‘CIFSSMBNegotiate’:
fs/cifs/cifssmb.c:605:3: warning: ‘strncpy’ writing 16 bytes into a region of size 1 overflows the destination [-Wstringop-overflow=]
strncpy(pSMB->DialectsArray+count, protocols[i].name, 16);
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Since we are already doing a strlen() on the source, change the strncpy
to a memcpy().
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
---
fs/cifs/cifssmb.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)
diff --git a/fs/cifs/cifssmb.c b/fs/cifs/cifssmb.c
index dc2f4cf08fe9..dcf939cb9d2f 100644
--- a/fs/cifs/cifssmb.c
+++ b/fs/cifs/cifssmb.c
@@ -601,10 +601,14 @@ CIFSSMBNegotiate(const unsigned int xid, struct cifs_ses *ses)
}
count = 0;
+ /*
+ * We know that all the name entries in the protocols array
+ * are short (< 16 bytes anyway) and are NUL terminated.
+ */
for (i = 0; i < CIFS_NUM_PROT; i++) {
- strncpy(pSMB->DialectsArray+count, protocols[i].name, 16);
- count += strlen(protocols[i].name) + 1;
- /* null at end of source and target buffers anyway */
+ size_t len = strlen(protocols[i].name) + 1;
+ memcpy(pSMB->DialectsArray+count, protocols[i].name, len);
+ count += len;
}
inc_rfc1001_len(pSMB, count);
pSMB->ByteCount = cpu_to_le16(count);
--
2.19.0.rc1
--
Cheers,
Stephen Rothwell
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^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] fs/cifs: suppress a string overflow warning
2018-09-03 3:15 [PATCH] fs/cifs: suppress a string overflow warning Stephen Rothwell
@ 2018-09-03 14:44 ` Steve French
2018-09-04 1:22 ` Stephen Rothwell
0 siblings, 1 reply; 4+ messages in thread
From: Steve French @ 2018-09-03 14:44 UTC (permalink / raw)
To: Stephen Rothwell; +Cc: Steve French, CIFS, samba-technical, LKML
Merged into cifs-2.6.git for-next
Is the message annoying enough on powerpc to merit going into
4.19-rc3, presumably should wait for 4.20?
On Sun, Sep 2, 2018 at 10:24 PM Stephen Rothwell <sfr@canb.auug.org.au> wrote:
>
> A powerpc build of cifs with gcc v8.2.0 produces this warning:
>
> fs/cifs/cifssmb.c: In function ‘CIFSSMBNegotiate’:
> fs/cifs/cifssmb.c:605:3: warning: ‘strncpy’ writing 16 bytes into a region of size 1 overflows the destination [-Wstringop-overflow=]
> strncpy(pSMB->DialectsArray+count, protocols[i].name, 16);
> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
> Since we are already doing a strlen() on the source, change the strncpy
> to a memcpy().
>
> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
> ---
> fs/cifs/cifssmb.c | 10 +++++++---
> 1 file changed, 7 insertions(+), 3 deletions(-)
>
> diff --git a/fs/cifs/cifssmb.c b/fs/cifs/cifssmb.c
> index dc2f4cf08fe9..dcf939cb9d2f 100644
> --- a/fs/cifs/cifssmb.c
> +++ b/fs/cifs/cifssmb.c
> @@ -601,10 +601,14 @@ CIFSSMBNegotiate(const unsigned int xid, struct cifs_ses *ses)
> }
>
> count = 0;
> + /*
> + * We know that all the name entries in the protocols array
> + * are short (< 16 bytes anyway) and are NUL terminated.
> + */
> for (i = 0; i < CIFS_NUM_PROT; i++) {
> - strncpy(pSMB->DialectsArray+count, protocols[i].name, 16);
> - count += strlen(protocols[i].name) + 1;
> - /* null at end of source and target buffers anyway */
> + size_t len = strlen(protocols[i].name) + 1;
> + memcpy(pSMB->DialectsArray+count, protocols[i].name, len);
> + count += len;
> }
> inc_rfc1001_len(pSMB, count);
> pSMB->ByteCount = cpu_to_le16(count);
> --
> 2.19.0.rc1
>
> --
> Cheers,
> Stephen Rothwell
--
Thanks,
Steve
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] fs/cifs: suppress a string overflow warning
2018-09-03 14:44 ` Steve French
@ 2018-09-04 1:22 ` Stephen Rothwell
2018-09-04 2:13 ` Steve French
0 siblings, 1 reply; 4+ messages in thread
From: Stephen Rothwell @ 2018-09-04 1:22 UTC (permalink / raw)
To: Steve French; +Cc: Steve French, CIFS, samba-technical, LKML
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Hi Steve,
On Mon, 3 Sep 2018 09:44:17 -0500 Steve French <smfrench@gmail.com> wrote:
>
> Merged into cifs-2.6.git for-next
>
> Is the message annoying enough on powerpc to merit going into
> 4.19-rc3, presumably should wait for 4.20?
Up to you, but 4.20 is probably fine.
--
Cheers,
Stephen Rothwell
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^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] fs/cifs: suppress a string overflow warning
2018-09-04 1:22 ` Stephen Rothwell
@ 2018-09-04 2:13 ` Steve French
0 siblings, 0 replies; 4+ messages in thread
From: Steve French @ 2018-09-04 2:13 UTC (permalink / raw)
To: Stephen Rothwell; +Cc: Steve French, CIFS, samba-technical, LKML
ok - it looks like it will be a little simpler if I wait
On Mon, Sep 3, 2018 at 8:22 PM Stephen Rothwell <sfr@canb.auug.org.au> wrote:
>
> Hi Steve,
>
> On Mon, 3 Sep 2018 09:44:17 -0500 Steve French <smfrench@gmail.com> wrote:
> >
> > Merged into cifs-2.6.git for-next
> >
> > Is the message annoying enough on powerpc to merit going into
> > 4.19-rc3, presumably should wait for 4.20?
>
> Up to you, but 4.20 is probably fine.
>
> --
> Cheers,
> Stephen Rothwell
--
Thanks,
Steve
^ permalink raw reply [flat|nested] 4+ messages in thread
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2018-09-03 3:15 [PATCH] fs/cifs: suppress a string overflow warning Stephen Rothwell
2018-09-03 14:44 ` Steve French
2018-09-04 1:22 ` Stephen Rothwell
2018-09-04 2:13 ` Steve French
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