2023-07-12 19:11:48

by Gustavo A. R. Silva

[permalink] [raw]
Subject: [PATCH][next] udf: Fix -Wstringop-overflow warnings

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 <[email protected]>
---
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,
--
2.34.1



2023-07-12 19:32:43

by Kees Cook

[permalink] [raw]
Subject: Re: [PATCH][next] udf: Fix -Wstringop-overflow warnings

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 <[email protected]>
> ---
> 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 <[email protected]>

--
Kees Cook

2023-07-31 19:19:20

by Jan Kara

[permalink] [raw]
Subject: Re: [PATCH][next] udf: Fix -Wstringop-overflow warnings

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 <[email protected]>
> > ---
> > 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 <[email protected]>

Thanks! I've merged the patch to my tree.

Honza
--
Jan Kara <[email protected]>
SUSE Labs, CR