Messages in this thread | | | Date | Wed, 2 Aug 2017 07:43:02 +1000 | From | Stephen Rothwell <> | Subject | Re: [PATCH 2/2] adfs: use 'unsigned' types for memcpy length |
| |
Hi Arnd,
On Tue, 1 Aug 2017 11:20:26 -0700 Kees Cook <keescook@chromium.org> wrote: > > On Tue, Aug 1, 2017 at 5:04 AM, Arnd Bergmann <arnd@arndb.de> wrote: > > After commit 62d1034f53e3 ("fortify: use WARN instead of BUG for now"), we > > get a warning in adfs about a possible buffer overflow: > > > > In function 'memcpy', > > inlined from '__adfs_dir_put' at fs/adfs/dir_f.c:318:2, > > inlined from 'adfs_f_update' at fs/adfs/dir_f.c:403:2: > > include/linux/string.h:305:4: error: call to '__read_overflow2' declared with attribute error: detected read beyond size of object passed as 2nd parameter > > __read_overflow2(); > > ^~~~~~~~~~~~~~~~~~ > > > > The warning is correct in the sense that a negative 'pos' argument > > to the function would have that result. However, this is not a bug, > > as we know the position is always positive (in fact, between 5 > > and 2007, inclusive) when the function gets called. > > > > Changing the variable to a unsigned type avoids the problem. I decided > > to use 'unsigned int' for the position in the directory and the block > > number, as they are both counting things, but use size_t for the > > offset and length that get passed into memcpy. This shuts up the > > warning. > > > > Signed-off-by: Arnd Bergmann <arnd@arndb.de> > > Acked-by: Kees Cook <keescook@chromium.org> > > Thanks for the fix! (Added sfr to Cc since he noticed this too.)
Can someone please send me the patch so I can use it if Andrew doesn't get around to updating mmotd today?
-- Cheers, Stephen Rothwell
| |