| Message ID | 20230619082019.656605-1-arnd@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v2] smb: avoid field overflow warning | expand |
On 6/19/2023 4:19 AM, Arnd Bergmann wrote: > From: Arnd Bergmann <arnd@arndb.de> > > 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 <arnd@arndb.de> > ---- > 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.
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,