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[Qemu-devel] [PATCH v2] linux-user/mmap.c: Avoid choosing NULL as start
From: |
Maximilian Riemensberger |
Subject: |
[Qemu-devel] [PATCH v2] linux-user/mmap.c: Avoid choosing NULL as start address |
Date: |
Sun, 7 Jan 2018 01:01:44 +0000 |
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 <address@hidden>
CC: Laurent Vivier <address@hidden>
CC: Peter Maydell <address@hidden>
Signed-off-by: Maximilian Riemensberger <address@hidden>
---
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
- [Qemu-devel] [PATCH v2] linux-user/mmap.c: Avoid choosing NULL as start address,
Maximilian Riemensberger <=