Clang can do some aggressive inlining, which provides it with greater
visibility into the sizes of various objects that are passed into
helpers. Specifically, compare_netdev_and_ip() can see through the type
given to the "sa" argument, which means it can generate code for "struct
sockaddr_in" that would have been passed to ipv6_addr_cmp() (that expects
to operate on the larger "struct sockaddr_in6"), which would result in a
compile-time buffer overflow condition detected by memcmp(). Logically,
this state isn't reachable due to the sa_family assignment two callers
above and the check in compare_netdev_and_ip(). Instead, provide a
compile-time check on sizes so the size-mismatched code will be elided
when inlining. Avoids the following warning from Clang:
../include/linux/fortify-string.h:652:4: error: call to '__read_overflow' declared with 'error' attribute: detected read beyond size of object (1st parameter)
__read_overflow();
^
note: In function 'cma_netevent_callback'
note: which inlined function 'node_from_ndev_ip'
1 error generated.
When the underlying object size is not known (e.g. with GCC and older
Clang), the result of __builtin_object_size() is SIZE_MAX, which
will also compile away, leaving the code as it was originally.
Link: https://github.com/ClangBuiltLinux/linux/issues/1687
Cc: Jason Gunthorpe <[email protected]>
Cc: Leon Romanovsky <[email protected]>
Cc: Mark Zhang <[email protected]>
Cc: Patrisious Haddad <[email protected]>
Cc: Nathan Chancellor <[email protected]>
Cc: Nick Desaulniers <[email protected]>
Cc: [email protected]
Cc: [email protected]
Signed-off-by: Kees Cook <[email protected]>
---
drivers/infiniband/core/cma.c | 17 ++++++++++++-----
1 file changed, 12 insertions(+), 5 deletions(-)
diff --git a/drivers/infiniband/core/cma.c b/drivers/infiniband/core/cma.c
index 1d2bff91d78b..308155937713 100644
--- a/drivers/infiniband/core/cma.c
+++ b/drivers/infiniband/core/cma.c
@@ -479,13 +479,20 @@ static int compare_netdev_and_ip(int ifindex_a, struct sockaddr *sa,
if (sa->sa_family != sb->sa_family)
return sa->sa_family - sb->sa_family;
- if (sa->sa_family == AF_INET)
- return memcmp((char *)&((struct sockaddr_in *)sa)->sin_addr,
- (char *)&((struct sockaddr_in *)sb)->sin_addr,
+ if (sa->sa_family == AF_INET &&
+ __builtin_object_size(sa, 0) >= sizeof(struct sockaddr_in)) {
+ return memcmp(&((struct sockaddr_in *)sa)->sin_addr,
+ &((struct sockaddr_in *)sb)->sin_addr,
sizeof(((struct sockaddr_in *)sa)->sin_addr));
+ }
+
+ if (sa->sa_family == AF_INET6 &&
+ __builtin_object_size(sa, 0) >= sizeof(struct sockaddr_in6)) {
+ return ipv6_addr_cmp(&((struct sockaddr_in6 *)sa)->sin6_addr,
+ &((struct sockaddr_in6 *)sb)->sin6_addr);
+ }
- return ipv6_addr_cmp(&((struct sockaddr_in6 *)sa)->sin6_addr,
- &((struct sockaddr_in6 *)sb)->sin6_addr);
+ return -1;
}
static int cma_add_id_to_tree(struct rdma_id_private *node_id_priv)
--
2.34.1
On Wed, Feb 08, 2023 at 03:25:53PM -0800, Kees Cook wrote:
> Clang can do some aggressive inlining, which provides it with greater
> visibility into the sizes of various objects that are passed into
> helpers. Specifically, compare_netdev_and_ip() can see through the type
> given to the "sa" argument, which means it can generate code for "struct
> sockaddr_in" that would have been passed to ipv6_addr_cmp() (that expects
> to operate on the larger "struct sockaddr_in6"), which would result in a
> compile-time buffer overflow condition detected by memcmp(). Logically,
> this state isn't reachable due to the sa_family assignment two callers
> above and the check in compare_netdev_and_ip(). Instead, provide a
> compile-time check on sizes so the size-mismatched code will be elided
> when inlining. Avoids the following warning from Clang:
>
> ../include/linux/fortify-string.h:652:4: error: call to '__read_overflow' declared with 'error' attribute: detected read beyond size of object (1st parameter)
> __read_overflow();
> ^
> note: In function 'cma_netevent_callback'
> note: which inlined function 'node_from_ndev_ip'
> 1 error generated.
>
> When the underlying object size is not known (e.g. with GCC and older
> Clang), the result of __builtin_object_size() is SIZE_MAX, which
> will also compile away, leaving the code as it was originally.
>
> Link: https://github.com/ClangBuiltLinux/linux/issues/1687
> Cc: Jason Gunthorpe <[email protected]>
> Cc: Leon Romanovsky <[email protected]>
> Cc: Mark Zhang <[email protected]>
> Cc: Patrisious Haddad <[email protected]>
> Cc: Nathan Chancellor <[email protected]>
> Cc: Nick Desaulniers <[email protected]>
> Cc: [email protected]
> Cc: [email protected]
> Signed-off-by: Kees Cook <[email protected]>
Tested-by: Nathan Chancellor <[email protected]> # build
Should this have a 'Cc: [email protected]', since we see this in
6.1?
> ---
> drivers/infiniband/core/cma.c | 17 ++++++++++++-----
> 1 file changed, 12 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/infiniband/core/cma.c b/drivers/infiniband/core/cma.c
> index 1d2bff91d78b..308155937713 100644
> --- a/drivers/infiniband/core/cma.c
> +++ b/drivers/infiniband/core/cma.c
> @@ -479,13 +479,20 @@ static int compare_netdev_and_ip(int ifindex_a, struct sockaddr *sa,
> if (sa->sa_family != sb->sa_family)
> return sa->sa_family - sb->sa_family;
>
> - if (sa->sa_family == AF_INET)
> - return memcmp((char *)&((struct sockaddr_in *)sa)->sin_addr,
> - (char *)&((struct sockaddr_in *)sb)->sin_addr,
> + if (sa->sa_family == AF_INET &&
> + __builtin_object_size(sa, 0) >= sizeof(struct sockaddr_in)) {
> + return memcmp(&((struct sockaddr_in *)sa)->sin_addr,
> + &((struct sockaddr_in *)sb)->sin_addr,
> sizeof(((struct sockaddr_in *)sa)->sin_addr));
> + }
> +
> + if (sa->sa_family == AF_INET6 &&
> + __builtin_object_size(sa, 0) >= sizeof(struct sockaddr_in6)) {
> + return ipv6_addr_cmp(&((struct sockaddr_in6 *)sa)->sin6_addr,
> + &((struct sockaddr_in6 *)sb)->sin6_addr);
> + }
>
> - return ipv6_addr_cmp(&((struct sockaddr_in6 *)sa)->sin6_addr,
> - &((struct sockaddr_in6 *)sb)->sin6_addr);
> + return -1;
> }
>
> static int cma_add_id_to_tree(struct rdma_id_private *node_id_priv)
> --
> 2.34.1
>
On Wed, Feb 08, 2023 at 03:25:53PM -0800, Kees Cook wrote:
> Clang can do some aggressive inlining, which provides it with greater
> visibility into the sizes of various objects that are passed into
> helpers. Specifically, compare_netdev_and_ip() can see through the type
> given to the "sa" argument, which means it can generate code for "struct
> sockaddr_in" that would have been passed to ipv6_addr_cmp() (that expects
> to operate on the larger "struct sockaddr_in6"), which would result in a
> compile-time buffer overflow condition detected by memcmp(). Logically,
> this state isn't reachable due to the sa_family assignment two callers
> above and the check in compare_netdev_and_ip(). Instead, provide a
> compile-time check on sizes so the size-mismatched code will be elided
> when inlining. Avoids the following warning from Clang:
>
> ../include/linux/fortify-string.h:652:4: error: call to '__read_overflow' declared with 'error' attribute: detected read beyond size of object (1st parameter)
> __read_overflow();
> ^
> note: In function 'cma_netevent_callback'
> note: which inlined function 'node_from_ndev_ip'
> 1 error generated.
>
> When the underlying object size is not known (e.g. with GCC and older
> Clang), the result of __builtin_object_size() is SIZE_MAX, which
> will also compile away, leaving the code as it was originally.
>
> Link: https://github.com/ClangBuiltLinux/linux/issues/1687
> Cc: Jason Gunthorpe <[email protected]>
> Cc: Leon Romanovsky <[email protected]>
> Cc: Mark Zhang <[email protected]>
> Cc: Patrisious Haddad <[email protected]>
> Cc: Nathan Chancellor <[email protected]>
> Cc: Nick Desaulniers <[email protected]>
> Cc: [email protected]
> Cc: [email protected]
> Signed-off-by: Kees Cook <[email protected]>
> Tested-by: Nathan Chancellor <[email protected]> # build
> ---
> drivers/infiniband/core/cma.c | 17 ++++++++++++-----
> 1 file changed, 12 insertions(+), 5 deletions(-)
This seems hacky, but I guess I can see why it is unreasonable for the
compiler to track the sa_family in this case.
Applied to for next
Jason