Hi Zhangjin,
On Wed, Jun 28, 2023 at 09:51:57PM +0800, Zhangjin Wu wrote:
Three mmap/munmap related test cases are added:
mmap_bad: the length argument must be greater than 0, otherwise, fail with -EINVAL.
munmap_bad: invalid (void *)-1 address fail with -EINVAL.
mmap_munmap_good: mmap() a file with good offset and then munmap().
Note, it is not easy to find a unique file for mmap() in different scenes, so, a file list is used to search the right one:
/proc/1/exe, for 'run' and 'run-user' target 'run-user' can not find '/proc/self/exe'
/proc/self/exe, for 'libc-test' target normal program 'libc-test' has no permission to access '/proc/1/exe'
Strictly speaking, if your executable is not readable (e.g. chmod 111 due to a restrictive umask) it will also fail that one.
- the others, for kernel without procfs let it pass even with 'worst case' kernel configs
You should include /dev/zero, which is commonly used to allocate anonymous memory and is more likely present and readable than any of the other files. And another file of choice is obviously argv[0] ;-) In this case you don't need any of the other extra ones. Thus I could suggest that you try in this order:
/dev/zero, /proc/self/exe, /proc/1/exe, argv[0]
and be done with it. That doesn't prevent one from extending the list if really needed later, but I doubt it would be needed. Also, it's already arranged in a read-write, then read-only fallbacks mode, so if we later need to add more complex tests involving writes, the writable /dev/zero will have precedence.
Willy