* [PATCH] dma-debug: Switch check from _text to _stext
@ 2016-01-04 18:48 Laura Abbott
2016-01-04 19:15 ` Kees Cook
0 siblings, 1 reply; 2+ messages in thread
From: Laura Abbott @ 2016-01-04 18:48 UTC (permalink / raw)
To: Andrew Morton
Cc: Laura Abbott, Russell King, Kees Cook, linux-kernel, Arnd Bergmann
>From include/asm-generic/sections.h:
/*
* Usage guidelines:
* _text, _data: architecture specific, don't use them in
* arch-independent code
* [_stext, _etext]: contains .text.* sections, may also contain
* .rodata.*
* and/or .init.* sections
_text is not guaranteed across architectures. Architectures such as ARM
may reuse parts which are not actually text and erroneously trigger a bug.
Switch to using _stext which is guaranteed to contain text sections.
Signed-off-by: Laura Abbott <labbott@fedoraproject.org>
---
Came out of https://lkml.kernel.org/g/<567B1176.4000106@redhat.com>
---
lib/dma-debug.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/lib/dma-debug.c b/lib/dma-debug.c
index d34bd24..4a1515f 100644
--- a/lib/dma-debug.c
+++ b/lib/dma-debug.c
@@ -1181,7 +1181,7 @@ static inline bool overlap(void *addr, unsigned long len, void *start, void *end
static void check_for_illegal_area(struct device *dev, void *addr, unsigned long len)
{
- if (overlap(addr, len, _text, _etext) ||
+ if (overlap(addr, len, _stext, _etext) ||
overlap(addr, len, __start_rodata, __end_rodata))
err_printk(dev, NULL, "DMA-API: device driver maps memory from kernel text or rodata [addr=%p] [len=%lu]\n", addr, len);
}
--
2.5.0
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] dma-debug: Switch check from _text to _stext
2016-01-04 18:48 [PATCH] dma-debug: Switch check from _text to _stext Laura Abbott
@ 2016-01-04 19:15 ` Kees Cook
0 siblings, 0 replies; 2+ messages in thread
From: Kees Cook @ 2016-01-04 19:15 UTC (permalink / raw)
To: Laura Abbott; +Cc: Andrew Morton, Russell King, LKML, Arnd Bergmann
On Mon, Jan 4, 2016 at 10:48 AM, Laura Abbott <labbott@fedoraproject.org> wrote:
> From include/asm-generic/sections.h:
>
> /*
> * Usage guidelines:
> * _text, _data: architecture specific, don't use them in
> * arch-independent code
> * [_stext, _etext]: contains .text.* sections, may also contain
> * .rodata.*
> * and/or .init.* sections
>
> _text is not guaranteed across architectures. Architectures such as ARM
> may reuse parts which are not actually text and erroneously trigger a bug.
> Switch to using _stext which is guaranteed to contain text sections.
>
> Signed-off-by: Laura Abbott <labbott@fedoraproject.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
-Kees
> ---
> Came out of https://lkml.kernel.org/g/<567B1176.4000106@redhat.com>
> ---
> lib/dma-debug.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/lib/dma-debug.c b/lib/dma-debug.c
> index d34bd24..4a1515f 100644
> --- a/lib/dma-debug.c
> +++ b/lib/dma-debug.c
> @@ -1181,7 +1181,7 @@ static inline bool overlap(void *addr, unsigned long len, void *start, void *end
>
> static void check_for_illegal_area(struct device *dev, void *addr, unsigned long len)
> {
> - if (overlap(addr, len, _text, _etext) ||
> + if (overlap(addr, len, _stext, _etext) ||
> overlap(addr, len, __start_rodata, __end_rodata))
> err_printk(dev, NULL, "DMA-API: device driver maps memory from kernel text or rodata [addr=%p] [len=%lu]\n", addr, len);
> }
> --
> 2.5.0
>
--
Kees Cook
Chrome OS & Brillo Security
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2016-01-04 19:15 ` Kees Cook
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