Commit 8526d84f authored Jan 31, 2018 by Konstantin Khlebnikov Committed by Linus Torvalds Jan 31, 2018

fs/proc/task_mmu.c: do not show VmExe bigger than total executable virtual memory

If start_code / end_code pointers are screwed then "VmExe" could be
bigger than total executable virtual memory and "VmLib" becomes
negative:

  VmExe:	  294320 kB
  VmLib:	18446744073709327564 kB

VmExe and VmLib documented as text segment and shared library code size.

Now their sum will be always equal to mm->exec_vm which sums size of
executable and not writable and not stack areas.

I've seen this for huge (>2Gb) statically linked binary which has whole
world inside.  For it start_code ..  end_code range also covers one of
rodata sections.  Probably this is bug in customized linker, elf loader
or both.

Anyway CONFIG_CHECKPOINT_RESTORE allows to change these pointers, thus
we cannot trust them without validation.

Link: http://lkml.kernel.org/r/150728955451.743749.11276392315459539583.stgit@buzz


Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent ef549e13

fs/proc/task_mmu.c

+8 −3

Original line number	Diff line number	Diff line
		@@ -47,8 +47,11 @@ void task_mem(struct seq_file m, struct mm_struct mm)
		if (hiwater_rss < mm->hiwater_rss)
		hiwater_rss = mm->hiwater_rss;

		text = (PAGE_ALIGN(mm->end_code) - (mm->start_code & PAGE_MASK)) >> 10;
		lib = (mm->exec_vm << (PAGE_SHIFT-10)) - text;
		/* split executable areas between text and lib */
		text = PAGE_ALIGN(mm->end_code) - (mm->start_code & PAGE_MASK);
		text = min(text, mm->exec_vm << PAGE_SHIFT);
		lib = (mm->exec_vm << PAGE_SHIFT) - text;

		swap = get_mm_counter(mm, MM_SWAPENTS);
		seq_printf(m,
		"VmPeak:\t%8lu kB\n"
		@@ -76,7 +79,9 @@ void task_mem(struct seq_file m, struct mm_struct mm)
		file << (PAGE_SHIFT-10),
		shmem << (PAGE_SHIFT-10),
		mm->data_vm << (PAGE_SHIFT-10),
		mm->stack_vm << (PAGE_SHIFT-10), text, lib,
		mm->stack_vm << (PAGE_SHIFT-10),
		text >> 10,
		lib >> 10,
		mm_pgtables_bytes(mm) >> 10,
		swap << (PAGE_SHIFT-10));
		hugetlb_report_usage(m, mm);

Admin message