From: Arnd Bergmann <[email protected]>
clang warns about a possible field overflow in a memcpy:
In file included from fs/smb/server/smb_common.c:7:
include/linux/fortify-string.h:583:4: error: call to '__write_overflow_field' declared with 'warning' attribute: detected write beyond size of field (1st parameter); maybe use struct_group()? [-Werror,-Wattribute-warning]
__write_overflow_field(p_size_field, size);
It appears to interpret the "&out[baselen + 4]" as referring to a single
byte of the character array, while the equivalen "out + baselen + 4" is
seen as an offset into the array.
I don't see that kind of warning elsewhere, so just go with the simple
rework.
Fixes: e2f34481b24db ("cifsd: add server-side procedures for SMB3")
Signed-off-by: Arnd Bergmann <[email protected]>
----
v2: fix typo in array length, and make sure it still addresses the warning
---
fs/smb/server/smb_common.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/smb/server/smb_common.c b/fs/smb/server/smb_common.c
index a7e81067bc991..39c6c8d7d0623 100644
--- a/fs/smb/server/smb_common.c
+++ b/fs/smb/server/smb_common.c
@@ -536,7 +536,7 @@ int ksmbd_extract_shortname(struct ksmbd_conn *conn, const char *longname,
out[baselen + 3] = PERIOD;
if (dot_present)
- memcpy(&out[baselen + 4], extension, 4);
+ memcpy(out + baselen + 4, extension, 4);
else
out[baselen + 4] = '\0';
smbConvertToUTF16((__le16 *)shortname, out, PATH_MAX,
--
2.39.2
On 6/19/2023 4:19 AM, Arnd Bergmann wrote:
> From: Arnd Bergmann <[email protected]>
>
> clang warns about a possible field overflow in a memcpy:
>
> In file included from fs/smb/server/smb_common.c:7:
> include/linux/fortify-string.h:583:4: error: call to '__write_overflow_field' declared with 'warning' attribute: detected write beyond size of field (1st parameter); maybe use struct_group()? [-Werror,-Wattribute-warning]
> __write_overflow_field(p_size_field, size);
>
> It appears to interpret the "&out[baselen + 4]" as referring to a single
> byte of the character array, while the equivalen "out + baselen + 4" is
> seen as an offset into the array.
>
> I don't see that kind of warning elsewhere, so just go with the simple
> rework.
>
> Fixes: e2f34481b24db ("cifsd: add server-side procedures for SMB3")
> Signed-off-by: Arnd Bergmann <[email protected]>
> ----
> v2: fix typo in array length, and make sure it still addresses the warning
> ---
> fs/smb/server/smb_common.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/smb/server/smb_common.c b/fs/smb/server/smb_common.c
> index a7e81067bc991..39c6c8d7d0623 100644
> --- a/fs/smb/server/smb_common.c
> +++ b/fs/smb/server/smb_common.c
> @@ -536,7 +536,7 @@ int ksmbd_extract_shortname(struct ksmbd_conn *conn, const char *longname,
> out[baselen + 3] = PERIOD;
>
> if (dot_present)
> - memcpy(&out[baselen + 4], extension, 4);
> + memcpy(out + baselen + 4, extension, 4);
> else
> out[baselen + 4] = '\0';
> smbConvertToUTF16((__le16 *)shortname, out, PATH_MAX,
It'd be really confusing to have the other two out[baselen + foo] = bar
in the lines above and below.
Can this be fixed more clearly with a new pointer, like
char *q = &out[baselen + 4];
memcpy(q, extension, 4);
??
Tom.