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flex_array: fix get function for elements in base starting at non-zero 

If all array elements fit into the base structure and data is copied using
flex_array_put() starting at a non-zero index, flex_array_get() will fail
to return the data.

This fixes the bug by only checking for NULL parts when all elements do
not fit in the base structure when flex_array_get() is used.  Otherwise,
fa_element_to_part_nr() will always be 0 since there are no parts
structures needed and such element may never have been put.  Thus, it will
remain NULL due to the kzalloc() of the base.

Additionally, flex_array_put() now only checks for a NULL part when all
elements do not fit in the base structure.  This is otherwise unnecessary
since the base structure is guaranteed to exist (or we would have already
hit a NULL pointer).

Signed-off-by: David Rientjes <rientjes@google.com>
Acked-by: Dave Hansen <dave@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
David Rientjes 2009-08-26 14:29:20 -07:00 committed by Linus Torvalds
parent 054b2b13cc
commit a30b595d2c
1 changed files with 8 additions and 6 deletions
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14
lib/flex_array.c
View File

@ -198,10 +198,11 @@ int flex_array_put(struct flex_array *fa, int element_nr, void *src, gfp_t flags
return -ENOSPC;
if (elements_fit_in_base(fa))
part = (struct flex_array_part *)&fa->parts[0];
else
else {
part = __fa_get_part(fa, part_nr, flags);
if (!part)
return -ENOMEM;
if (!part)
return -ENOMEM;
}
dst = &part->elements[index_inside_part(fa, element_nr)];
memcpy(dst, src, fa->element_size);
return 0;
@ -257,11 +258,12 @@ void *flex_array_get(struct flex_array *fa, int element_nr)
if (element_nr >= fa->total_nr_elements)
return NULL;
if (!fa->parts[part_nr])
return NULL;
if (elements_fit_in_base(fa))
part = (struct flex_array_part *)&fa->parts[0];
else
else {
part = fa->parts[part_nr];
if (!part)
return NULL;
}
return &part->elements[index_inside_part(fa, element_nr)];
}