* [PATCH] linux-user: Correctly start brk after executable
@ 2020-07-28 22:46 Timothy E Baldwin
2020-07-29 15:47 ` Richard Henderson
2020-09-05 20:51 ` Laurent Vivier
0 siblings, 2 replies; 3+ messages in thread
From: Timothy E Baldwin @ 2020-07-28 22:46 UTC (permalink / raw)
To: Laurent Vivier, qemu-devel; +Cc: Timothy E Baldwin
info->brk was erroneously set to the end of highest addressed
writable segment which could result it in overlapping the executable.
As per load_elf_binary in fs/binfmt_elf.c in Linux, it should be
set to end of highest addressed segment.
Signed-off-by: Timothy E Baldwin <T.E.Baldwin99@members.leeds.ac.uk>
---
linux-user/elfload.c | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)
diff --git a/linux-user/elfload.c b/linux-user/elfload.c
index 7e7f642332..d5d444f698 100644
--- a/linux-user/elfload.c
+++ b/linux-user/elfload.c
@@ -2564,9 +2564,9 @@ static void load_elf_image(const char *image_name, int image_fd,
if (vaddr_ef > info->end_data) {
info->end_data = vaddr_ef;
}
- if (vaddr_em > info->brk) {
- info->brk = vaddr_em;
- }
+ }
+ if (vaddr_em > info->brk) {
+ info->brk = vaddr_em;
}
} else if (eppnt->p_type == PT_INTERP && pinterp_name) {
char *interp_name;
@@ -2621,7 +2621,6 @@ static void load_elf_image(const char *image_name, int image_fd,
if (info->end_data == 0) {
info->start_data = info->end_code;
info->end_data = info->end_code;
- info->brk = info->end_code;
}
if (qemu_log_enabled()) {
--
2.25.1
Given an executable with a read-write segment between 2 executable segments
qemu was unmapping most of the execuateble instead of area reserved for brk
at the end of the execuatable.
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] linux-user: Correctly start brk after executable
2020-07-28 22:46 [PATCH] linux-user: Correctly start brk after executable Timothy E Baldwin
@ 2020-07-29 15:47 ` Richard Henderson
2020-09-05 20:51 ` Laurent Vivier
1 sibling, 0 replies; 3+ messages in thread
From: Richard Henderson @ 2020-07-29 15:47 UTC (permalink / raw)
To: Timothy E Baldwin, Laurent Vivier, qemu-devel
On 7/28/20 3:46 PM, Timothy E Baldwin wrote:
> info->brk was erroneously set to the end of highest addressed
> writable segment which could result it in overlapping the executable.
>
> As per load_elf_binary in fs/binfmt_elf.c in Linux, it should be
> set to end of highest addressed segment.
>
> Signed-off-by: Timothy E Baldwin <T.E.Baldwin99@members.leeds.ac.uk>
> ---
> linux-user/elfload.c | 7 +++----
> 1 file changed, 3 insertions(+), 4 deletions(-)
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
r~
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] linux-user: Correctly start brk after executable
2020-07-28 22:46 [PATCH] linux-user: Correctly start brk after executable Timothy E Baldwin
2020-07-29 15:47 ` Richard Henderson
@ 2020-09-05 20:51 ` Laurent Vivier
1 sibling, 0 replies; 3+ messages in thread
From: Laurent Vivier @ 2020-09-05 20:51 UTC (permalink / raw)
To: Timothy E Baldwin, qemu-devel
Le 29/07/2020 à 00:46, Timothy E Baldwin a écrit :
> info->brk was erroneously set to the end of highest addressed
> writable segment which could result it in overlapping the executable.
>
> As per load_elf_binary in fs/binfmt_elf.c in Linux, it should be
> set to end of highest addressed segment.
>
> Signed-off-by: Timothy E Baldwin <T.E.Baldwin99@members.leeds.ac.uk>
> ---
> linux-user/elfload.c | 7 +++----
> 1 file changed, 3 insertions(+), 4 deletions(-)
>
> diff --git a/linux-user/elfload.c b/linux-user/elfload.c
> index 7e7f642332..d5d444f698 100644
> --- a/linux-user/elfload.c
> +++ b/linux-user/elfload.c
> @@ -2564,9 +2564,9 @@ static void load_elf_image(const char *image_name, int image_fd,
> if (vaddr_ef > info->end_data) {
> info->end_data = vaddr_ef;
> }
> - if (vaddr_em > info->brk) {
> - info->brk = vaddr_em;
> - }
> + }
> + if (vaddr_em > info->brk) {
> + info->brk = vaddr_em;
> }
> } else if (eppnt->p_type == PT_INTERP && pinterp_name) {
> char *interp_name;
> @@ -2621,7 +2621,6 @@ static void load_elf_image(const char *image_name, int image_fd,
> if (info->end_data == 0) {
> info->start_data = info->end_code;
> info->end_data = info->end_code;
> - info->brk = info->end_code;
> }
>
> if (qemu_log_enabled()) {
>
Applied to my linux-user-for-5.2 branch.
Thanks,
Laurent
^ permalink raw reply [flat|nested] 3+ messages in thread
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2020-07-28 22:46 [PATCH] linux-user: Correctly start brk after executable Timothy E Baldwin
2020-07-29 15:47 ` Richard Henderson
2020-09-05 20:51 ` Laurent Vivier
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