* [PATCH] linux-user/elfload: munmap proper address in pgd_find_hole_fallback
@ 2021-01-31 6:18 Vincent Fazio
2021-02-13 21:37 ` Laurent Vivier
` (2 more replies)
0 siblings, 3 replies; 5+ messages in thread
From: Vincent Fazio @ 2021-01-31 6:18 UTC (permalink / raw)
To: qemu-devel; +Cc: qemu-trivial, laurent, Vincent Fazio
From: Vincent Fazio <vfazio@gmail.com>
Previously, if the build host's libc did not define MAP_FIXED_NOREPLACE
or if the running kernel didn't support that flag, it was possible for
pgd_find_hole_fallback to munmap an incorrect address which could lead to
SIGSEGV if the range happened to overlap with the mapped address of the
QEMU binary.
mmap(0x1000, 22261224, PROT_NONE, MAP_PRIVATE|MAP_ANONYMOUS|MAP_NORESERVE, -1, 0) = 0x7f889d331000
munmap(0x1000, 22261224) = 0
--- SIGSEGV {si_signo=SIGSEGV, si_code=SEGV_MAPERR, si_addr=0x84b817} ---
++ killed by SIGSEGV +++
Now, always munmap the address returned by mmap.
Fixes: 2667e069e7b5 ("linux-user: don't use MAP_FIXED in pgd_find_hole_fallback")
Signed-off-by: Vincent Fazio <vfazio@gmail.com>
---
linux-user/elfload.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/linux-user/elfload.c b/linux-user/elfload.c
index a64050713f..5f5f23d2e5 100644
--- a/linux-user/elfload.c
+++ b/linux-user/elfload.c
@@ -2216,7 +2216,7 @@ static uintptr_t pgd_find_hole_fallback(uintptr_t guest_size, uintptr_t brk,
void * mmap_start = mmap((void *) align_start, guest_size,
PROT_NONE, flags, -1, 0);
if (mmap_start != MAP_FAILED) {
- munmap((void *) align_start, guest_size);
+ munmap(mmap_start, guest_size);
if (MAP_FIXED_NOREPLACE != 0 ||
mmap_start == (void *) align_start) {
return (uintptr_t) mmap_start + offset;
--
2.30.0
^ permalink raw reply related [flat|nested] 5+ messages in thread* Re: [PATCH] linux-user/elfload: munmap proper address in pgd_find_hole_fallback
2021-01-31 6:18 [PATCH] linux-user/elfload: munmap proper address in pgd_find_hole_fallback Vincent Fazio
@ 2021-02-13 21:37 ` Laurent Vivier
2021-02-14 11:32 ` Alex Bennée
2021-03-09 21:23 ` Laurent Vivier
2 siblings, 0 replies; 5+ messages in thread
From: Laurent Vivier @ 2021-02-13 21:37 UTC (permalink / raw)
To: Vincent Fazio, qemu-devel; +Cc: qemu-trivial, Alex Bennée, Vincent Fazio
Le 31/01/2021 à 07:18, Vincent Fazio a écrit :
> From: Vincent Fazio <vfazio@gmail.com>
Please, use the same email address to send your patch.
>
> Previously, if the build host's libc did not define MAP_FIXED_NOREPLACE
> or if the running kernel didn't support that flag, it was possible for
> pgd_find_hole_fallback to munmap an incorrect address which could lead to
> SIGSEGV if the range happened to overlap with the mapped address of the
> QEMU binary.
>
> mmap(0x1000, 22261224, PROT_NONE, MAP_PRIVATE|MAP_ANONYMOUS|MAP_NORESERVE, -1, 0) = 0x7f889d331000
> munmap(0x1000, 22261224) = 0
> --- SIGSEGV {si_signo=SIGSEGV, si_code=SEGV_MAPERR, si_addr=0x84b817} ---
> ++ killed by SIGSEGV +++
>
> Now, always munmap the address returned by mmap.
>
> Fixes: 2667e069e7b5 ("linux-user: don't use MAP_FIXED in pgd_find_hole_fallback")
> Signed-off-by: Vincent Fazio <vfazio@gmail.com>
> ---
> linux-user/elfload.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/linux-user/elfload.c b/linux-user/elfload.c
> index a64050713f..5f5f23d2e5 100644
> --- a/linux-user/elfload.c
> +++ b/linux-user/elfload.c
> @@ -2216,7 +2216,7 @@ static uintptr_t pgd_find_hole_fallback(uintptr_t guest_size, uintptr_t brk,
> void * mmap_start = mmap((void *) align_start, guest_size,
> PROT_NONE, flags, -1, 0);
> if (mmap_start != MAP_FAILED) {
> - munmap((void *) align_start, guest_size);
> + munmap(mmap_start, guest_size);
> if (MAP_FIXED_NOREPLACE != 0 ||
> mmap_start == (void *) align_start) {
> return (uintptr_t) mmap_start + offset;
>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
CC: Alex
Thanks,
Laurent
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH] linux-user/elfload: munmap proper address in pgd_find_hole_fallback
2021-01-31 6:18 [PATCH] linux-user/elfload: munmap proper address in pgd_find_hole_fallback Vincent Fazio
2021-02-13 21:37 ` Laurent Vivier
@ 2021-02-14 11:32 ` Alex Bennée
2021-03-09 21:04 ` Vincent Fazio
2021-03-09 21:23 ` Laurent Vivier
2 siblings, 1 reply; 5+ messages in thread
From: Alex Bennée @ 2021-02-14 11:32 UTC (permalink / raw)
To: Vincent Fazio; +Cc: qemu-trivial, laurent, Vincent Fazio, qemu-devel
Vincent Fazio <vfazio@xes-inc.com> writes:
> From: Vincent Fazio <vfazio@gmail.com>
>
> Previously, if the build host's libc did not define MAP_FIXED_NOREPLACE
> or if the running kernel didn't support that flag, it was possible for
> pgd_find_hole_fallback to munmap an incorrect address which could lead to
> SIGSEGV if the range happened to overlap with the mapped address of the
> QEMU binary.
>
> mmap(0x1000, 22261224, PROT_NONE, MAP_PRIVATE|MAP_ANONYMOUS|MAP_NORESERVE, -1, 0) = 0x7f889d331000
> munmap(0x1000, 22261224) = 0
> --- SIGSEGV {si_signo=SIGSEGV, si_code=SEGV_MAPERR, si_addr=0x84b817} ---
> ++ killed by SIGSEGV +++
>
> Now, always munmap the address returned by mmap.
>
> Fixes: 2667e069e7b5 ("linux-user: don't use MAP_FIXED in pgd_find_hole_fallback")
> Signed-off-by: Vincent Fazio <vfazio@gmail.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
--
Alex Bennée
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH] linux-user/elfload: munmap proper address in pgd_find_hole_fallback
2021-02-14 11:32 ` Alex Bennée
@ 2021-03-09 21:04 ` Vincent Fazio
0 siblings, 0 replies; 5+ messages in thread
From: Vincent Fazio @ 2021-03-09 21:04 UTC (permalink / raw)
To: laurent; +Cc: qemu-trivial, Alex Bennée, qemu-devel, Vincent Fazio
Pinging per Laurent.
On 2/14/21 5:32 AM, Alex Bennée wrote:
>
> Vincent Fazio <vfazio@xes-inc.com> writes:
>
>> From: Vincent Fazio <vfazio@gmail.com>
>>
>> Previously, if the build host's libc did not define MAP_FIXED_NOREPLACE
>> or if the running kernel didn't support that flag, it was possible for
>> pgd_find_hole_fallback to munmap an incorrect address which could lead to
>> SIGSEGV if the range happened to overlap with the mapped address of the
>> QEMU binary.
>>
>> mmap(0x1000, 22261224, PROT_NONE, MAP_PRIVATE|MAP_ANONYMOUS|MAP_NORESERVE, -1, 0) = 0x7f889d331000
>> munmap(0x1000, 22261224) = 0
>> --- SIGSEGV {si_signo=SIGSEGV, si_code=SEGV_MAPERR, si_addr=0x84b817} ---
>> ++ killed by SIGSEGV +++
>>
>> Now, always munmap the address returned by mmap.
>>
>> Fixes: 2667e069e7b5 ("linux-user: don't use MAP_FIXED in pgd_find_hole_fallback")
>> Signed-off-by: Vincent Fazio <vfazio@gmail.com>
>
> Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] linux-user/elfload: munmap proper address in pgd_find_hole_fallback
2021-01-31 6:18 [PATCH] linux-user/elfload: munmap proper address in pgd_find_hole_fallback Vincent Fazio
2021-02-13 21:37 ` Laurent Vivier
2021-02-14 11:32 ` Alex Bennée
@ 2021-03-09 21:23 ` Laurent Vivier
2 siblings, 0 replies; 5+ messages in thread
From: Laurent Vivier @ 2021-03-09 21:23 UTC (permalink / raw)
To: Vincent Fazio, qemu-devel; +Cc: qemu-trivial, Vincent Fazio
Le 31/01/2021 à 07:18, Vincent Fazio a écrit :
> From: Vincent Fazio <vfazio@gmail.com>
>
> Previously, if the build host's libc did not define MAP_FIXED_NOREPLACE
> or if the running kernel didn't support that flag, it was possible for
> pgd_find_hole_fallback to munmap an incorrect address which could lead to
> SIGSEGV if the range happened to overlap with the mapped address of the
> QEMU binary.
>
> mmap(0x1000, 22261224, PROT_NONE, MAP_PRIVATE|MAP_ANONYMOUS|MAP_NORESERVE, -1, 0) = 0x7f889d331000
> munmap(0x1000, 22261224) = 0
> --- SIGSEGV {si_signo=SIGSEGV, si_code=SEGV_MAPERR, si_addr=0x84b817} ---
> ++ killed by SIGSEGV +++
>
> Now, always munmap the address returned by mmap.
>
> Fixes: 2667e069e7b5 ("linux-user: don't use MAP_FIXED in pgd_find_hole_fallback")
> Signed-off-by: Vincent Fazio <vfazio@gmail.com>
> ---
> linux-user/elfload.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/linux-user/elfload.c b/linux-user/elfload.c
> index a64050713f..5f5f23d2e5 100644
> --- a/linux-user/elfload.c
> +++ b/linux-user/elfload.c
> @@ -2216,7 +2216,7 @@ static uintptr_t pgd_find_hole_fallback(uintptr_t guest_size, uintptr_t brk,
> void * mmap_start = mmap((void *) align_start, guest_size,
> PROT_NONE, flags, -1, 0);
> if (mmap_start != MAP_FAILED) {
> - munmap((void *) align_start, guest_size);
> + munmap(mmap_start, guest_size);
> if (MAP_FIXED_NOREPLACE != 0 ||
> mmap_start == (void *) align_start) {
> return (uintptr_t) mmap_start + offset;
>
Applied to my linux-user-for-6.0 branch.
Thanks,
Laurent
^ permalink raw reply [flat|nested] 5+ messages in thread
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2021-01-31 6:18 [PATCH] linux-user/elfload: munmap proper address in pgd_find_hole_fallback Vincent Fazio
2021-02-13 21:37 ` Laurent Vivier
2021-02-14 11:32 ` Alex Bennée
2021-03-09 21:04 ` Vincent Fazio
2021-03-09 21:23 ` Laurent Vivier
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