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[PATCH v5 06/31] linux-user: Check for overflow in access_ok
From: |
Richard Henderson |
Subject: |
[PATCH v5 06/31] linux-user: Check for overflow in access_ok |
Date: |
Wed, 3 Feb 2021 08:59:45 -1000 |
Verify that addr + size - 1 does not wrap around.
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
linux-user/qemu.h | 17 ++++++++++++-----
1 file changed, 12 insertions(+), 5 deletions(-)
diff --git a/linux-user/qemu.h b/linux-user/qemu.h
index 17aa992165..441ba6a78b 100644
--- a/linux-user/qemu.h
+++ b/linux-user/qemu.h
@@ -491,12 +491,19 @@ extern unsigned long guest_stack_size;
#define VERIFY_READ 0
#define VERIFY_WRITE 1 /* implies read access */
-static inline int access_ok(int type, abi_ulong addr, abi_ulong size)
+static inline bool access_ok(int type, abi_ulong addr, abi_ulong size)
{
- return guest_addr_valid(addr) &&
- (size == 0 || guest_addr_valid(addr + size - 1)) &&
- page_check_range((target_ulong)addr, size,
- (type == VERIFY_READ) ? PAGE_READ : (PAGE_READ |
PAGE_WRITE)) == 0;
+ if (!guest_addr_valid(addr)) {
+ return false;
+ }
+ if (size != 0 &&
+ (addr + size - 1 < addr ||
+ !guest_addr_valid(addr + size - 1))) {
+ return false;
+ }
+ return page_check_range((target_ulong)addr, size,
+ (type == VERIFY_READ) ? PAGE_READ :
+ (PAGE_READ | PAGE_WRITE)) == 0;
}
/* NOTE __get_user and __put_user use host pointers and don't check access.
--
2.25.1
- [PATCH v5 00/31] target-arm: Implement ARMv8.5-MemTag, user mode, Richard Henderson, 2021/02/03
- [PATCH v5 01/31] tcg: Introduce target-specific page data for user-only, Richard Henderson, 2021/02/03
- [PATCH v5 05/31] exec: Improve types for guest_addr_valid, Richard Henderson, 2021/02/03
- [PATCH v5 06/31] linux-user: Check for overflow in access_ok,
Richard Henderson <=
- [PATCH v5 02/31] linux-user: Introduce PAGE_ANON, Richard Henderson, 2021/02/03
- [PATCH v5 07/31] linux-user: Tidy VERIFY_READ/VERIFY_WRITE, Richard Henderson, 2021/02/03
- [PATCH v5 08/31] bsd-user: Tidy VERIFY_READ/VERIFY_WRITE, Richard Henderson, 2021/02/03
- [PATCH v5 10/31] linux-user: Fix guest_addr_valid vs reserved_va, Richard Henderson, 2021/02/03
- [PATCH v5 13/31] linux-user: Explicitly untag memory management syscalls, Richard Henderson, 2021/02/03
- [PATCH v5 03/31] exec: Use uintptr_t for guest_base, Richard Henderson, 2021/02/03