m68k 54418 fails to execute user space
Michael Schmitz
schmitzmic at gmail.com
Fri Jun 28 00:48:08 PDT 2024
Jean-Michel,
Am 28.06.2024 um 19:24 schrieb Jean-Michel Hautbois:
>> I forgot to take into account that libraries are loaded only the
>> binary starts executing. Can you print the same map dump in the exit
>> syscall code path? That ought to show all loaded libraries at that point.
>
> Thanks for your suggestion !
> I changed it a bit, and I added a call in do_exit() as suggested. When
> executing ls I get:
>
> bash-5.2# ls -l
> load_elf_binary: Dump memory for ls (31):
> mmap: 60000000-6001e000 r-xp 00000000 00:00 178 /lib/ld.so.1
> mmap: 6001e000-60022000 rw-p 0001c000 00:00 178 /lib/ld.so.1
> mmap: 70000000-700c2000 r-xp 00000000 00:00 28 /bin/busybox
> mmap: 700c2000-700ca000 rw-p 000c0000 00:00 28 /bin/busybox
> mmap: bfc1e000-bfc40000 rw-p bffde000 00:00 0 [stack]
>
> do_exit: Dump memory for ls (31):
> mmap: 60000000-6001e000 r-xp 00000000 00:00 178 /lib/ld.so.1
> mmap: 6001e000-60020000 r--p 0001c000 00:00 178 /lib/ld.so.1
> mmap: 60020000-60022000 rw-p 0001e000 00:00 178 /lib/ld.so.1
> mmap: 60022000-6002c000 r-xp 00000000 00:00 193 /lib/libresolv.so.2
> mmap: 6002c000-6002e000 r--p 00008000 00:00 193 /lib/libresolv.so.2
> mmap: 6002e000-60030000 rw-p 0000a000 00:00 193 /lib/libresolv.so.2
> mmap: 60030000-60032000 rw-p 60030000 00:00 0
> mmap: 60032000-6015a000 r-xp 00000000 00:00 185 /lib/libc.so.6
> mmap: 6015a000-6015c000 r--p 00126000 00:00 185 /lib/libc.so.6
> mmap: 6015c000-60160000 rw-p 00128000 00:00 185 /lib/libc.so.6
> mmap: 60160000-6016e000 rw-p 60160000 00:00 0
> mmap: 70000000-700c2000 r-xp 00000000 00:00 28 /bin/busybox
> mmap: 700c2000-700c4000 r--p 000c0000 00:00 28 /bin/busybox
> mmap: 700c4000-700ca000 rw-p 000c2000 00:00 28 /bin/busybox
> mmap: 700ca000-700ec000 rwxp 700ca000 00:00 0 [heap]
> mmap: bfc1e000-bfc40000 rw-p bffde000 00:00 0 [stack]
>
> When I call it a second time, I get:
>
> bash-5.2# ls -l
> load_elf_binary: Dump memory for ls (33):
> mmap: 60000000-6001e000 r-xp 00000000 00:00 178 /lib/ld.so.1
> mmap: 6001e000-60022000 rw-p 0001c000 00:00 178 /lib/ld.so.1
> mmap: 70000000-700c2000 r-xp 00000000 00:00 28 /bin/busybox
> mmap: 700c2000-700ca000 rw-p 000c0000 00:00 28 /bin/busybox
> mmap: bfb5a000-bfb7c000 rw-p bffde000 00:00 0 [stack]
> do_exit: Dump memory for ls (33):
> mmap: 60000000-6001e000 r-xp 00000000 00:00 178 /lib/ld.so.1
> mmap: 6001e000-60020000 r--p 0001c000 00:00 178 /lib/ld.so.1
> mmap: 60020000-60022000 rw-p 0001e000 00:00 178 /lib/ld.so.1
> mmap: 60022000-6002c000 r-xp 00000000 00:00 193 /lib/libresolv.so.2
> mmap: 6002c000-6002e000 r--p 00008000 00:00 193 /lib/libresolv.so.2
> mmap: 6002e000-60030000 rw-p 0000a000 00:00 193 /lib/libresolv.so.2
> mmap: 60030000-60032000 rw-p 60030000 00:00 0
> mmap: 60032000-6015a000 r-xp 00000000 00:00 185 /lib/libc.so.6
> mmap: 6015a000-6015c000 r--p 00126000 00:00 185 /lib/libc.so.6
> mmap: 6015c000-60160000 rw-p 00128000 00:00 185 /lib/libc.so.6
> mmap: 60160000-6016e000 rw-p 60160000 00:00 0
> mmap: 70000000-700c2000 r-xp 00000000 00:00 28 /bin/busybox
> mmap: 700c2000-700c4000 r--p 000c0000 00:00 28 /bin/busybox
> mmap: 700c4000-700ca000 rw-p 000c2000 00:00 28 /bin/busybox
No heap in this second call. Can you print mm->start_brk and mm->brk please?
The process memory layout is a little unusual (I would have expected the
binary to be mapped before the dynamic libraries, not after). Is that
expected on Coldfire, Greg?
Cheers,
Michael
> mmap: bfb5a000-bfb7c000 rw-p bffde000 00:00 0 [stack]
>
> The first call generates the "ls" output, not the second one.
> The helper looks like:
> diff --git a/mm/mmap.c b/mm/mmap.c
> index 83b4682ec85c..14d861e9cba2 100644
> --- a/mm/mmap.c
> +++ b/mm/mmap.c
> @@ -76,6 +76,87 @@ int mmap_rnd_compat_bits __read_mostly =
> CONFIG_ARCH_MMAP_RND_COMPAT_BITS;
> static bool ignore_rlimit_data;
> core_param(ignore_rlimit_data, ignore_rlimit_data, bool, 0644);
>
> +int dump_memory_map(struct task_struct *task)
> +{
> + struct mm_struct *mm = task->mm;
> + struct vm_area_struct *vma;
> + struct file *file;
> + struct path *path;
> + char *buf;
> + char *pathname;
> +
> + if (!mm) {
> + return -ENOMEM;
> + }
> +
> + MA_STATE(mas, &mm->mm_mt, 0, -1);
> + // Acquire the read lock for mmap_lock
> + down_read(&mm->mmap_lock);
> + mas_lock(&mas);
> + for (vma = mas_find(&mas, ULONG_MAX); vma; vma = mas_find(&mas,
> ULONG_MAX)) {
> + char perms[5] = "---p"; // Default permissions
> + // Set permissions based on vm_flags
> + if (vma->vm_flags & VM_READ) perms[0] = 'r';
> + if (vma->vm_flags & VM_WRITE) perms[1] = 'w';
> + if (vma->vm_flags & VM_EXEC) perms[2] = 'x';
> + if (vma->vm_flags & VM_MAYSHARE) perms[3] = 's';
> +
> + if (vma->vm_file) { // If there's an associated file
> + buf = (char *)__get_free_page(GFP_KERNEL);
> + if (!buf) {
> + continue; // Handle memory allocation
> failure
> + }
> +
> + file = vma->vm_file;
> + path = &file->f_path;
> + pathname = d_path(path, buf, PAGE_SIZE);
> + if (IS_ERR(pathname)) {
> + pathname = NULL;
> + }
> +
> + // Print memory area information with file path
> + pr_info("%08lx-%08lx %s %08lx %02x:%02x %lu %s\n",
> + vma->vm_start, vma->vm_end,
> + perms,
> + vma->vm_pgoff << PAGE_SHIFT,
> + MAJOR(file_inode(file)->i_rdev),
> + MINOR(file_inode(file)->i_rdev),
> + file_inode(file)->i_ino,
> + pathname ? pathname : "");
> +
> + free_page((unsigned long)buf);
> + } else {
> + char *special_area_name = NULL;
> +
> + // Check for heap
> + if (vma->vm_end > mm->start_brk && vma->vm_start
> < mm->brk) {
> + special_area_name = "[heap]";
> + }
> + // Check for stack
> + else if (vma->vm_start <= mm->start_stack &&
> vma->vm_end >= mm->start_stack) {
> + special_area_name = "[stack]";
> + }
> + // Check for vdso
> + else if (vma->vm_flags & VM_EXEC &&
> vma->vm_flags & VM_READ && !vma->vm_file) {
> + special_area_name = "[vdso]";
> + }
> +
> + // Print memory area information without file path
> + pr_info("%08lx-%08lx %s %08lx 00:00 0 %s\n",
> + vma->vm_start, vma->vm_end,
> + perms,
> + vma->vm_pgoff << PAGE_SHIFT,
> + special_area_name ? special_area_name :
> " ");
> + }
> + }
> + mas_unlock(&mas);
> + // Release the read lock for mmap_lock
> + up_read(&mm->mmap_lock);
> +
> + return 0;
> +}
> +EXPORT_SYMBOL(dump_memory_map);
>
>
> Thanks,
> JM
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