| Message ID | 20210817102709.15046-1-len.baker@gmx.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | CIFS: Fix a potencially linear read overflow | expand |
Len Baker <len.baker@gmx.com> writes: > strlcpy() reads the entire source buffer first. This read may exceed the > destination size limit. This is both inefficient and can lead to linear > read overflows if a source string is not NUL-terminated. > > Also, the strnlen() call does not avoid the read overflow in the strlcpy > function when a not NUL-terminated string is passed. > > So, replace this block by a call to kstrndup() that avoids this type of > overflow and does the same. > > Fixes: 066ce6899484d ("cifs: rename cifs_strlcpy_to_host and make it use new functions") > Signed-off-by: Len Baker <len.baker@gmx.com> > --- > fs/cifs/cifs_unicode.c | 9 ++------- > 1 file changed, 2 insertions(+), 7 deletions(-) Reviewed-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
tentatively merged into cifs-2.6.git for-next pending testing On Tue, Aug 17, 2021 at 7:29 PM Paulo Alcantara <pc@cjr.nz> wrote: > > Len Baker <len.baker@gmx.com> writes: > > > strlcpy() reads the entire source buffer first. This read may exceed the > > destination size limit. This is both inefficient and can lead to linear > > read overflows if a source string is not NUL-terminated. > > > > Also, the strnlen() call does not avoid the read overflow in the strlcpy > > function when a not NUL-terminated string is passed. > > > > So, replace this block by a call to kstrndup() that avoids this type of > > overflow and does the same. > > > > Fixes: 066ce6899484d ("cifs: rename cifs_strlcpy_to_host and make it use new functions") > > Signed-off-by: Len Baker <len.baker@gmx.com> > > --- > > fs/cifs/cifs_unicode.c | 9 ++------- > > 1 file changed, 2 insertions(+), 7 deletions(-) > > Reviewed-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
On Tue, 2021-08-17 at 12:27 +0200, Len Baker wrote: > strlcpy() reads the entire source buffer first. This read may exceed the > destination size limit. This is both inefficient and can lead to linear > read overflows if a source string is not NUL-terminated. > > Also, the strnlen() call does not avoid the read overflow in the strlcpy > function when a not NUL-terminated string is passed. > > So, replace this block by a call to kstrndup() that avoids this type of > overflow and does the same. > > Fixes: 066ce6899484d ("cifs: rename cifs_strlcpy_to_host and make it use new functions") > Signed-off-by: Len Baker <len.baker@gmx.com> > --- > fs/cifs/cifs_unicode.c | 9 ++------- > 1 file changed, 2 insertions(+), 7 deletions(-) > > diff --git a/fs/cifs/cifs_unicode.c b/fs/cifs/cifs_unicode.c > index 9bd03a231032..171ad8b42107 100644 > --- a/fs/cifs/cifs_unicode.c > +++ b/fs/cifs/cifs_unicode.c > @@ -358,14 +358,9 @@ cifs_strndup_from_utf16(const char *src, const int maxlen, > if (!dst) > return NULL; > cifs_from_utf16(dst, (__le16 *) src, len, maxlen, codepage, > - NO_MAP_UNI_RSVD); > + NO_MAP_UNI_RSVD); > } else { > - len = strnlen(src, maxlen); > - len++; > - dst = kmalloc(len, GFP_KERNEL); > - if (!dst) > - return NULL; > - strlcpy(dst, src, len); > + dst = kstrndup(src, maxlen, GFP_KERNEL); > } > > return dst; > -- > 2.25.1 > Reviewed-by: Jeff Layton <jlayton@kernel.org>
Added RB and repushed to cifs-2.6.git for-next On Wed, Aug 18, 2021 at 8:22 AM Jeff Layton <jlayton@kernel.org> wrote: > > On Tue, 2021-08-17 at 12:27 +0200, Len Baker wrote: > > strlcpy() reads the entire source buffer first. This read may exceed the > > destination size limit. This is both inefficient and can lead to linear > > read overflows if a source string is not NUL-terminated. > > > > Also, the strnlen() call does not avoid the read overflow in the strlcpy > > function when a not NUL-terminated string is passed. > > > > So, replace this block by a call to kstrndup() that avoids this type of > > overflow and does the same. > > > > Fixes: 066ce6899484d ("cifs: rename cifs_strlcpy_to_host and make it use new functions") > > Signed-off-by: Len Baker <len.baker@gmx.com> > > --- > > fs/cifs/cifs_unicode.c | 9 ++------- > > 1 file changed, 2 insertions(+), 7 deletions(-) > > > > diff --git a/fs/cifs/cifs_unicode.c b/fs/cifs/cifs_unicode.c > > index 9bd03a231032..171ad8b42107 100644 > > --- a/fs/cifs/cifs_unicode.c > > +++ b/fs/cifs/cifs_unicode.c > > @@ -358,14 +358,9 @@ cifs_strndup_from_utf16(const char *src, const int maxlen, > > if (!dst) > > return NULL; > > cifs_from_utf16(dst, (__le16 *) src, len, maxlen, codepage, > > - NO_MAP_UNI_RSVD); > > + NO_MAP_UNI_RSVD); > > } else { > > - len = strnlen(src, maxlen); > > - len++; > > - dst = kmalloc(len, GFP_KERNEL); > > - if (!dst) > > - return NULL; > > - strlcpy(dst, src, len); > > + dst = kstrndup(src, maxlen, GFP_KERNEL); > > } > > > > return dst; > > -- > > 2.25.1 > > > > Reviewed-by: Jeff Layton <jlayton@kernel.org> >
diff --git a/fs/cifs/cifs_unicode.c b/fs/cifs/cifs_unicode.c index 9bd03a231032..171ad8b42107 100644 --- a/fs/cifs/cifs_unicode.c +++ b/fs/cifs/cifs_unicode.c @@ -358,14 +358,9 @@ cifs_strndup_from_utf16(const char *src, const int maxlen, if (!dst) return NULL; cifs_from_utf16(dst, (__le16 *) src, len, maxlen, codepage, - NO_MAP_UNI_RSVD); + NO_MAP_UNI_RSVD); } else { - len = strnlen(src, maxlen); - len++; - dst = kmalloc(len, GFP_KERNEL); - if (!dst) - return NULL; - strlcpy(dst, src, len); + dst = kstrndup(src, maxlen, GFP_KERNEL); } return dst;
strlcpy() reads the entire source buffer first. This read may exceed the destination size limit. This is both inefficient and can lead to linear read overflows if a source string is not NUL-terminated. Also, the strnlen() call does not avoid the read overflow in the strlcpy function when a not NUL-terminated string is passed. So, replace this block by a call to kstrndup() that avoids this type of overflow and does the same. Fixes: 066ce6899484d ("cifs: rename cifs_strlcpy_to_host and make it use new functions") Signed-off-by: Len Baker <len.baker@gmx.com> --- fs/cifs/cifs_unicode.c | 9 ++------- 1 file changed, 2 insertions(+), 7 deletions(-) -- 2.25.1