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flex_arrays: allow zero length flex arrays

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Just like kmalloc will allow one to allocate a 0 length segment of memory
flex arrays should do the same thing.  It should bomb if you try to use
something, but it should at least allow the allocation.

This is needed because when SELinux switched to using flex_arrays in 2.6.38
the inability to allocate a 0 length array resulted in SELinux policy load
returning -ENOSPC when previously it worked.

Based-on-patch-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Eric Paris <eparis@redhat.com>
Tested-by: Chris Richards <gizmo@giz-works.com>
Cc: stable@kernel.org [2.6.38+]
This commit is contained in:
Eric Paris 2011-04-28 15:55:52 -04:00
parent 5a3ea8782c
commit 150cdf6ec0
1 changed files with 10 additions and 1 deletions
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11
lib/flex_array.c
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@ -253,9 +253,16 @@ int flex_array_prealloc(struct flex_array *fa, unsigned int start,
unsigned int end;
struct flex_array_part *part;
if (!start && !nr_elements)
return 0;
if (start >= fa->total_nr_elements)
return -ENOSPC;
if (!nr_elements)
return 0;
end = start + nr_elements - 1;
if (start >= fa->total_nr_elements || end >= fa->total_nr_elements)
if (end >= fa->total_nr_elements)
return -ENOSPC;
if (elements_fit_in_base(fa))
return 0;
@ -346,6 +353,8 @@ int flex_array_shrink(struct flex_array *fa)
int part_nr;
int ret = 0;
if (!fa->total_nr_elements)
return 0;
if (elements_fit_in_base(fa))
return ret;
for (part_nr = 0; part_nr < FLEX_ARRAY_NR_BASE_PTRS; part_nr++) {