On Tue, Aug 1, 2017 at 5:04 AM, Arnd Bergmann <[email protected]> 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 <[email protected]>
Acked-by: Kees Cook <[email protected]> Thanks for the fix! (Added sfr to Cc since he noticed this too.) -Kees -- Kees Cook Pixel Security
