Re: m68k 54418 fails to execute user space

[Jean-Michel Hautbois <jeanmichel.hautbois@yoseli.org>]

Michael,

On 28/06/2024 09:48, Michael Schmitz wrote:
> 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?

Sure:
mmap: start_brk: 700ca000, brk: 700ca000

> 
> 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