* [Qemu-devel] [PATCH v2] linux-user/mmap.c: Avoid choosing NULL as start address
@ 2018-01-07 1:01 Maximilian Riemensberger
2018-01-07 12:39 ` Laurent Vivier
` (2 more replies)
0 siblings, 3 replies; 4+ messages in thread
From: Maximilian Riemensberger @ 2018-01-07 1:01 UTC (permalink / raw)
To: qemu-devel
Cc: Maximilian Riemensberger, Riku Voipio, Laurent Vivier, Peter Maydell
mmap() is required by the linux kernel ABI and POSIX to return a
non-NULL address when the implementation chooses a start address for the
mapping.
The current implementation of mmap_find_vma_reserved() can return NULL
as start address of a mapping which leads to subsequent crashes inside
the guests glibc, e.g. output of qemu-arm-static --strace executing a
test binary stx_test:
1879 mmap2(NULL,8388608,PROT_READ|PROT_WRITE,MAP_PRIVATE|MAP_ANONYMOUS|0x20000,-1,0) = 0x00000000
1879 write(2,0xf6fd39d0,79) stx_test: allocatestack.c:514: allocate_stack: Assertion `mem != NULL' failed.
This patch fixes mmap_find_vma_reserved() by skipping NULL as start
address while searching for a suitable mapping start address.
CC: Riku Voipio <riku.voipio@iki.fi>
CC: Laurent Vivier <laurent@vivier.eu>
CC: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Maximilian Riemensberger <riemensberger@cadami.net>
---
Changes since v1:
- Applied feedback from Laurent Vivier
linux-user/mmap.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/linux-user/mmap.c b/linux-user/mmap.c
index 4888f53..0fbfd6d 100644
--- a/linux-user/mmap.c
+++ b/linux-user/mmap.c
@@ -234,7 +234,7 @@ static abi_ulong mmap_find_vma_reserved(abi_ulong start, abi_ulong size)
if (prot) {
end_addr = addr;
}
- if (addr + size == end_addr) {
+ if (addr && addr + size == end_addr) {
break;
}
addr -= qemu_host_page_size;
--
2.7.4
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [Qemu-devel] [PATCH v2] linux-user/mmap.c: Avoid choosing NULL as start address
2018-01-07 1:01 [Qemu-devel] [PATCH v2] linux-user/mmap.c: Avoid choosing NULL as start address Maximilian Riemensberger
@ 2018-01-07 12:39 ` Laurent Vivier
2018-01-08 20:28 ` Richard Henderson
2018-01-19 16:34 ` Laurent Vivier
2 siblings, 0 replies; 4+ messages in thread
From: Laurent Vivier @ 2018-01-07 12:39 UTC (permalink / raw)
To: Maximilian Riemensberger, qemu-devel; +Cc: Riku Voipio, Peter Maydell
Le 07/01/2018 à 02:01, Maximilian Riemensberger a écrit :
> mmap() is required by the linux kernel ABI and POSIX to return a
> non-NULL address when the implementation chooses a start address for the
> mapping.
>
> The current implementation of mmap_find_vma_reserved() can return NULL
> as start address of a mapping which leads to subsequent crashes inside
> the guests glibc, e.g. output of qemu-arm-static --strace executing a
> test binary stx_test:
>
> 1879 mmap2(NULL,8388608,PROT_READ|PROT_WRITE,MAP_PRIVATE|MAP_ANONYMOUS|0x20000,-1,0) = 0x00000000
> 1879 write(2,0xf6fd39d0,79) stx_test: allocatestack.c:514: allocate_stack: Assertion `mem != NULL' failed.
>
> This patch fixes mmap_find_vma_reserved() by skipping NULL as start
> address while searching for a suitable mapping start address.
>
> CC: Riku Voipio <riku.voipio@iki.fi>
> CC: Laurent Vivier <laurent@vivier.eu>
> CC: Peter Maydell <peter.maydell@linaro.org>
> Signed-off-by: Maximilian Riemensberger <riemensberger@cadami.net>
> ---
> Changes since v1:
> - Applied feedback from Laurent Vivier
>
> linux-user/mmap.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/linux-user/mmap.c b/linux-user/mmap.c
> index 4888f53..0fbfd6d 100644
> --- a/linux-user/mmap.c
> +++ b/linux-user/mmap.c
> @@ -234,7 +234,7 @@ static abi_ulong mmap_find_vma_reserved(abi_ulong start, abi_ulong size)
> if (prot) {
> end_addr = addr;
> }
> - if (addr + size == end_addr) {
> + if (addr && addr + size == end_addr) {
> break;
> }
> addr -= qemu_host_page_size;
>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [Qemu-devel] [PATCH v2] linux-user/mmap.c: Avoid choosing NULL as start address
2018-01-07 1:01 [Qemu-devel] [PATCH v2] linux-user/mmap.c: Avoid choosing NULL as start address Maximilian Riemensberger
2018-01-07 12:39 ` Laurent Vivier
@ 2018-01-08 20:28 ` Richard Henderson
2018-01-19 16:34 ` Laurent Vivier
2 siblings, 0 replies; 4+ messages in thread
From: Richard Henderson @ 2018-01-08 20:28 UTC (permalink / raw)
To: Maximilian Riemensberger, qemu-devel
Cc: Peter Maydell, Riku Voipio, Laurent Vivier
On 01/06/2018 05:01 PM, Maximilian Riemensberger wrote:
> mmap() is required by the linux kernel ABI and POSIX to return a
> non-NULL address when the implementation chooses a start address for the
> mapping.
>
> The current implementation of mmap_find_vma_reserved() can return NULL
> as start address of a mapping which leads to subsequent crashes inside
> the guests glibc, e.g. output of qemu-arm-static --strace executing a
> test binary stx_test:
>
> 1879 mmap2(NULL,8388608,PROT_READ|PROT_WRITE,MAP_PRIVATE|MAP_ANONYMOUS|0x20000,-1,0) = 0x00000000
> 1879 write(2,0xf6fd39d0,79) stx_test: allocatestack.c:514: allocate_stack: Assertion `mem != NULL' failed.
>
> This patch fixes mmap_find_vma_reserved() by skipping NULL as start
> address while searching for a suitable mapping start address.
>
> CC: Riku Voipio <riku.voipio@iki.fi>
> CC: Laurent Vivier <laurent@vivier.eu>
> CC: Peter Maydell <peter.maydell@linaro.org>
> Signed-off-by: Maximilian Riemensberger <riemensberger@cadami.net>
> ---
> Changes since v1:
> - Applied feedback from Laurent Vivier
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
r~
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [Qemu-devel] [PATCH v2] linux-user/mmap.c: Avoid choosing NULL as start address
2018-01-07 1:01 [Qemu-devel] [PATCH v2] linux-user/mmap.c: Avoid choosing NULL as start address Maximilian Riemensberger
2018-01-07 12:39 ` Laurent Vivier
2018-01-08 20:28 ` Richard Henderson
@ 2018-01-19 16:34 ` Laurent Vivier
2 siblings, 0 replies; 4+ messages in thread
From: Laurent Vivier @ 2018-01-19 16:34 UTC (permalink / raw)
To: Maximilian Riemensberger, qemu-devel; +Cc: Peter Maydell, Riku Voipio
Le 07/01/2018 à 02:01, Maximilian Riemensberger a écrit :
> mmap() is required by the linux kernel ABI and POSIX to return a
> non-NULL address when the implementation chooses a start address for the
> mapping.
>
> The current implementation of mmap_find_vma_reserved() can return NULL
> as start address of a mapping which leads to subsequent crashes inside
> the guests glibc, e.g. output of qemu-arm-static --strace executing a
> test binary stx_test:
>
> 1879 mmap2(NULL,8388608,PROT_READ|PROT_WRITE,MAP_PRIVATE|MAP_ANONYMOUS|0x20000,-1,0) = 0x00000000
> 1879 write(2,0xf6fd39d0,79) stx_test: allocatestack.c:514: allocate_stack: Assertion `mem != NULL' failed.
>
> This patch fixes mmap_find_vma_reserved() by skipping NULL as start
> address while searching for a suitable mapping start address.
>
> CC: Riku Voipio <riku.voipio@iki.fi>
> CC: Laurent Vivier <laurent@vivier.eu>
> CC: Peter Maydell <peter.maydell@linaro.org>
> Signed-off-by: Maximilian Riemensberger <riemensberger@cadami.net>
> ---
> Changes since v1:
> - Applied feedback from Laurent Vivier
>
> linux-user/mmap.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/linux-user/mmap.c b/linux-user/mmap.c
> index 4888f53..0fbfd6d 100644
> --- a/linux-user/mmap.c
> +++ b/linux-user/mmap.c
> @@ -234,7 +234,7 @@ static abi_ulong mmap_find_vma_reserved(abi_ulong start, abi_ulong size)
> if (prot) {
> end_addr = addr;
> }
> - if (addr + size == end_addr) {
> + if (addr && addr + size == end_addr) {
> break;
> }
> addr -= qemu_host_page_size;
>
Applied to my linux-user branch.
Thanks,
Laurent
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2018-01-19 16:34 UTC | newest]
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2018-01-07 1:01 [Qemu-devel] [PATCH v2] linux-user/mmap.c: Avoid choosing NULL as start address Maximilian Riemensberger
2018-01-07 12:39 ` Laurent Vivier
2018-01-08 20:28 ` Richard Henderson
2018-01-19 16:34 ` Laurent Vivier
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