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linux-user: Use MAP_FIXED_NOREPLACE for initial image mmap

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Use this as extra protection for the guest mapping over
any qemu host mappings.

Tested-by: Helge Deller <deller@gmx.de>
Reviewed-by: Helge Deller <deller@gmx.de>
Reviewed-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
This commit is contained in:
Richard Henderson 2023-08-03 17:55:28 +00:00
parent da2b71fab6
commit ad25051bae
1 changed files with 6 additions and 3 deletions
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9
linux-user/elfload.c
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@ -3147,8 +3147,11 @@ static void load_elf_image(const char *image_name, int image_fd,
/*
* Reserve address space for all of this.
*
* In the case of ET_EXEC, we supply MAP_FIXED so that we get
* exactly the address range that is required.
* In the case of ET_EXEC, we supply MAP_FIXED_NOREPLACE so that we get
* exactly the address range that is required. Without reserved_va,
* the guest address space is not isolated. We have attempted to avoid
* conflict with the host program itself via probe_guest_base, but using
* MAP_FIXED_NOREPLACE instead of MAP_FIXED provides an extra check.
*
* Otherwise this is ET_DYN, and we are searching for a location
* that can hold the memory space required. If the image is
@ -3160,7 +3163,7 @@ static void load_elf_image(const char *image_name, int image_fd,
*/
load_addr = target_mmap(loaddr, (size_t)hiaddr - loaddr + 1, PROT_NONE,
MAP_PRIVATE | MAP_ANON | MAP_NORESERVE |
(ehdr->e_type == ET_EXEC ? MAP_FIXED : 0),
(ehdr->e_type == ET_EXEC ? MAP_FIXED_NOREPLACE : 0),
-1, 0);
if (load_addr == -1) {
goto exit_mmap;