[v3] bsd-user mmap fixes

[PATCH v3 9/9] bsd-user/mmap.c: assert that target_mprotect cannot fail

Posted by Warner Losh 4 years, 4 months ago

Similar to the equivalent linux-user change 86abac06c14. All error
conditions that target_mprotect checks are also checked by target_mmap.
EACCESS cannot happen because we are just removing PROT_WRITE.  ENOMEM
should not happen because we are modifying a whole VMA (and we have
bigger problems anyway if it happens).

Fixes a Coverity false positive, where Coverity complains about
target_mprotect's return value being passed to tb_invalidate_phys_range.

Signed-off-by: Mikaël Urankar <mikael.urankar@gmail.com>
Signed-off-by: Warner Losh <imp@bsdimp.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
---
 bsd-user/mmap.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/bsd-user/mmap.c b/bsd-user/mmap.c
index 066d9c10ff..4586ad27d0 100644
--- a/bsd-user/mmap.c
+++ b/bsd-user/mmap.c
@@ -604,10 +604,7 @@ abi_long target_mmap(abi_ulong start, abi_ulong len, int prot,
             }
             if (!(prot & PROT_WRITE)) {
                 ret = target_mprotect(start, len, prot);
-                if (ret != 0) {
-                    start = ret;
-                    goto the_end;
-                }
+                assert(ret == 0);
             }
             goto the_end;
         }
-- 
2.32.0

Re: [PATCH v3 9/9] bsd-user/mmap.c: assert that target_mprotect cannot fail

Posted by Kyle Evans 4 years, 3 months ago

On Fri, Oct 8, 2021 at 4:31 PM Warner Losh <imp@bsdimp.com> wrote:
>
> Similar to the equivalent linux-user change 86abac06c14. All error
> conditions that target_mprotect checks are also checked by target_mmap.
> EACCESS cannot happen because we are just removing PROT_WRITE.  ENOMEM
> should not happen because we are modifying a whole VMA (and we have
> bigger problems anyway if it happens).
>
> Fixes a Coverity false positive, where Coverity complains about
> target_mprotect's return value being passed to tb_invalidate_phys_range.
>
> Signed-off-by: Mikaël Urankar <mikael.urankar@gmail.com>
> Signed-off-by: Warner Losh <imp@bsdimp.com>
> Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
> Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
> ---
>  bsd-user/mmap.c | 5 +----
>  1 file changed, 1 insertion(+), 4 deletions(-)
>
> diff --git a/bsd-user/mmap.c b/bsd-user/mmap.c
> index 066d9c10ff..4586ad27d0 100644
> --- a/bsd-user/mmap.c
> +++ b/bsd-user/mmap.c
> @@ -604,10 +604,7 @@ abi_long target_mmap(abi_ulong start, abi_ulong len, int prot,
>              }
>              if (!(prot & PROT_WRITE)) {
>                  ret = target_mprotect(start, len, prot);
> -                if (ret != 0) {
> -                    start = ret;
> -                    goto the_end;
> -                }
> +                assert(ret == 0);
>              }
>              goto the_end;
>          }
> --
> 2.32.0
>
>

Reviewed-by: Kyle Evans <kevans@FreeBSD.org>