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R. Silva" , Jan Kara , linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org Subject: Re: [PATCH][next] udf: Fix -Wstringop-overflow warnings Message-ID: <20230731143523.rfmn6oqob7pofyan@quack3> References: <202307121204.36EF4C1@keescook> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <202307121204.36EF4C1@keescook> Precedence: bulk List-ID: X-Mailing-List: linux-hardening@vger.kernel.org On Wed 12-07-23 12:05:34, Kees Cook wrote: > On Wed, Jul 12, 2023 at 12:25:45PM -0600, Gustavo A. R. Silva wrote: > > Use unsigned type in call to macro mint_t(). This avoids confusing the > > compiler about possible negative values that would cause the value in > > _len_ to wrap around. > > > > Fixes the following -Wstringop-warnings seen when building ARM > > architecture with allyesconfig (GCC 13): > > fs/udf/directory.c: In function 'udf_copy_fi': > > include/linux/fortify-string.h:57:33: warning: '__builtin_memcpy' specified bound between 2147483648 and 4294967295 exceeds maximum object size 2147483647 [-Wstringop-overflow=] > > 57 | #define __underlying_memcpy __builtin_memcpy > > | ^ > > include/linux/fortify-string.h:648:9: note: in expansion of macro '__underlying_memcpy' > > 648 | __underlying_##op(p, q, __fortify_size); \ > > | ^~~~~~~~~~~~~ > > include/linux/fortify-string.h:693:26: note: in expansion of macro '__fortify_memcpy_chk' > > 693 | #define memcpy(p, q, s) __fortify_memcpy_chk(p, q, s, \ > > | ^~~~~~~~~~~~~~~~~~~~ > > fs/udf/directory.c:99:9: note: in expansion of macro 'memcpy' > > 99 | memcpy(&iter->fi, iter->bh[0]->b_data + off, len); > > | ^~~~~~ > > include/linux/fortify-string.h:57:33: warning: '__builtin_memcpy' specified bound between 2147483648 and 4294967295 exceeds maximum object size 2147483647 [-Wstringop-overflow=] > > 57 | #define __underlying_memcpy __builtin_memcpy > > | ^ > > include/linux/fortify-string.h:648:9: note: in expansion of macro '__underlying_memcpy' > > 648 | __underlying_##op(p, q, __fortify_size); \ > > | ^~~~~~~~~~~~~ > > include/linux/fortify-string.h:693:26: note: in expansion of macro '__fortify_memcpy_chk' > > 693 | #define memcpy(p, q, s) __fortify_memcpy_chk(p, q, s, \ > > | ^~~~~~~~~~~~~~~~~~~~ > > fs/udf/directory.c:99:9: note: in expansion of macro 'memcpy' > > 99 | memcpy(&iter->fi, iter->bh[0]->b_data + off, len); > > | ^~~~~~ > > AR fs/udf/built-in.a > > > > This helps with the ongoing efforts to globally enable > > -Wstringop-overflow. > > > > Link: https://github.com/KSPP/linux/issues/329 > > Signed-off-by: Gustavo A. R. Silva > > --- > > fs/udf/directory.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/fs/udf/directory.c b/fs/udf/directory.c > > index 1c775e072b2f..93153665eb37 100644 > > --- a/fs/udf/directory.c > > +++ b/fs/udf/directory.c > > @@ -95,7 +95,7 @@ static int udf_copy_fi(struct udf_fileident_iter *iter) > > } > > > > off = iter->pos & (blksize - 1); > > - len = min_t(int, sizeof(struct fileIdentDesc), blksize - off); > > + len = min_t(u32, sizeof(struct fileIdentDesc), blksize - off); > > memcpy(&iter->fi, iter->bh[0]->b_data + off, len); > > if (len < sizeof(struct fileIdentDesc)) > > memcpy((char *)(&iter->fi) + len, iter->bh[1]->b_data, > > len is u32, "off" can't be less than blksize, so this all looks correct > to me. Thanks! > > Reviewed-by: Kees Cook Thanks! I've merged the patch to my tree. Honza -- Jan Kara SUSE Labs, CR