* [PATCH] Add missing __syscall_ret in dl_mmap
@ 2019-02-09 13:34 Ilya Matveychikov
2019-02-09 14:35 ` Rich Felker
2019-02-09 14:56 ` [PATCH] Fix the use of syscall result " Ilya Matveychikov
0 siblings, 2 replies; 4+ messages in thread
From: Ilya Matveychikov @ 2019-02-09 13:34 UTC (permalink / raw)
To: musl
Signed-off-by: Ilya V. Matveychikov <matvejchikov@gmail.com>
---
ldso/dynlink.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/ldso/dynlink.c b/ldso/dynlink.c
index ec921df..329b42a 100644
--- a/ldso/dynlink.c
+++ b/ldso/dynlink.c
@@ -904,6 +904,7 @@ static void *dl_mmap(size_t n)
#else
p = (void *)__syscall(SYS_mmap, 0, n, prot, flags, -1, 0);
#endif
+ p = (void *)__syscall_ret((unsigned long)p);
return p == MAP_FAILED ? 0 : p;
}
--
2.7.4
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] Add missing __syscall_ret in dl_mmap
2019-02-09 13:34 [PATCH] Add missing __syscall_ret in dl_mmap Ilya Matveychikov
@ 2019-02-09 14:35 ` Rich Felker
2019-02-09 14:56 ` [PATCH] Fix the use of syscall result " Ilya Matveychikov
1 sibling, 0 replies; 4+ messages in thread
From: Rich Felker @ 2019-02-09 14:35 UTC (permalink / raw)
To: musl
On Sat, Feb 09, 2019 at 05:34:02PM +0400, Ilya Matveychikov wrote:
> Signed-off-by: Ilya V. Matveychikov <matvejchikov@gmail.com>
> ---
> ldso/dynlink.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/ldso/dynlink.c b/ldso/dynlink.c
> index ec921df..329b42a 100644
> --- a/ldso/dynlink.c
> +++ b/ldso/dynlink.c
> @@ -904,6 +904,7 @@ static void *dl_mmap(size_t n)
> #else
> p = (void *)__syscall(SYS_mmap, 0, n, prot, flags, -1, 0);
> #endif
> + p = (void *)__syscall_ret((unsigned long)p);
> return p == MAP_FAILED ? 0 : p;
> }
I think you're right that the calling code expects dl_mmap to return
0, not a negative error code cast to an invalid pointer, on failure.
However the change above is wrong. The whole reason the dl_mmap
function exists is that it's used at a point at which non-static
function calls can't be made (technically, calls to hidden functions
probably work but it's not a property that we rely on), and at which
accessing TLS (and thus errno in the error path) is not yet possible.
The right fix would probably be something like:
return (uintptr_t)p > -4096 ? 0 : p;
Out of curiousity, how did you come across this?
Rich
^ permalink raw reply [flat|nested] 4+ messages in thread
* [PATCH] Fix the use of syscall result in dl_mmap
2019-02-09 13:34 [PATCH] Add missing __syscall_ret in dl_mmap Ilya Matveychikov
2019-02-09 14:35 ` Rich Felker
@ 2019-02-09 14:56 ` Ilya Matveychikov
2019-04-06 13:40 ` Rich Felker
1 sibling, 1 reply; 4+ messages in thread
From: Ilya Matveychikov @ 2019-02-09 14:56 UTC (permalink / raw)
To: musl; +Cc: dalias
Correct version of the change thanks to Rich Felker!
I was not cc-ed, so here is the discussion:
https://www.openwall.com/lists/musl/2019/02/09/2
Signed-off-by: Ilya V. Matveychikov <matvejchikov@gmail.com>
---
ldso/dynlink.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/ldso/dynlink.c b/ldso/dynlink.c
index ec921df..76e8c06 100644
--- a/ldso/dynlink.c
+++ b/ldso/dynlink.c
@@ -904,7 +904,7 @@ static void *dl_mmap(size_t n)
#else
p = (void *)__syscall(SYS_mmap, 0, n, prot, flags, -1, 0);
#endif
- return p == MAP_FAILED ? 0 : p;
+ return (unsigned long)p > -4096UL ? 0 : p;
}
static void makefuncdescs(struct dso *p)
—
2.7.4
> On Feb 9, 2019, at 5:34 PM, Ilya Matveychikov <matvejchikov@gmail.com> wrote:
>
> Signed-off-by: Ilya V. Matveychikov <matvejchikov@gmail.com>
> ---
> ldso/dynlink.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/ldso/dynlink.c b/ldso/dynlink.c
> index ec921df..329b42a 100644
> --- a/ldso/dynlink.c
> +++ b/ldso/dynlink.c
> @@ -904,6 +904,7 @@ static void *dl_mmap(size_t n)
> #else
> p = (void *)__syscall(SYS_mmap, 0, n, prot, flags, -1, 0);
> #endif
> + p = (void *)__syscall_ret((unsigned long)p);
> return p == MAP_FAILED ? 0 : p;
> }
>
> --
> 2.7.4
>
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] Fix the use of syscall result in dl_mmap
2019-02-09 14:56 ` [PATCH] Fix the use of syscall result " Ilya Matveychikov
@ 2019-04-06 13:40 ` Rich Felker
0 siblings, 0 replies; 4+ messages in thread
From: Rich Felker @ 2019-04-06 13:40 UTC (permalink / raw)
To: Ilya Matveychikov; +Cc: musl
On Sat, Feb 09, 2019 at 06:56:17PM +0400, Ilya Matveychikov wrote:
> Correct version of the change thanks to Rich Felker!
>
> I was not cc-ed, so here is the discussion:
> https://www.openwall.com/lists/musl/2019/02/09/2
Thanks! Sorry I overlooked this before. I'm applying it now.
Rich
> Signed-off-by: Ilya V. Matveychikov <matvejchikov@gmail.com>
> ---
> ldso/dynlink.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/ldso/dynlink.c b/ldso/dynlink.c
> index ec921df..76e8c06 100644
> --- a/ldso/dynlink.c
> +++ b/ldso/dynlink.c
> @@ -904,7 +904,7 @@ static void *dl_mmap(size_t n)
> #else
> p = (void *)__syscall(SYS_mmap, 0, n, prot, flags, -1, 0);
> #endif
> - return p == MAP_FAILED ? 0 : p;
> + return (unsigned long)p > -4096UL ? 0 : p;
> }
>
> static void makefuncdescs(struct dso *p)
> —
> 2.7.4
>
>
> > On Feb 9, 2019, at 5:34 PM, Ilya Matveychikov <matvejchikov@gmail.com> wrote:
> >
> > Signed-off-by: Ilya V. Matveychikov <matvejchikov@gmail.com>
> > ---
> > ldso/dynlink.c | 1 +
> > 1 file changed, 1 insertion(+)
> >
> > diff --git a/ldso/dynlink.c b/ldso/dynlink.c
> > index ec921df..329b42a 100644
> > --- a/ldso/dynlink.c
> > +++ b/ldso/dynlink.c
> > @@ -904,6 +904,7 @@ static void *dl_mmap(size_t n)
> > #else
> > p = (void *)__syscall(SYS_mmap, 0, n, prot, flags, -1, 0);
> > #endif
> > + p = (void *)__syscall_ret((unsigned long)p);
> > return p == MAP_FAILED ? 0 : p;
> > }
> >
> > --
> > 2.7.4
> >
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2019-04-06 13:40 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
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2019-02-09 13:34 [PATCH] Add missing __syscall_ret in dl_mmap Ilya Matveychikov
2019-02-09 14:35 ` Rich Felker
2019-02-09 14:56 ` [PATCH] Fix the use of syscall result " Ilya Matveychikov
2019-04-06 13:40 ` Rich Felker
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