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padata: use integer wrap around to prevent deadlock on seq_nr overflow

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commit 9a22b28123 upstream.

When submitting more than 2^32 padata objects to padata_do_serial, the
current sorting implementation incorrectly sorts padata objects with
overflowed seq_nr, causing them to be placed before existing objects in
the reorder list. This leads to a deadlock in the serialization process
as padata_find_next cannot match padata->seq_nr and pd->processed
because the padata instance with overflowed seq_nr will be selected
next.

To fix this, we use an unsigned integer wrap around to correctly sort
padata objects in scenarios with integer overflow.

Fixes: bfde23ce20 ("padata: unbind parallel jobs from specific CPUs")
Cc: <stable@vger.kernel.org>
Co-developed-by: Christian Gafert <christian.gafert@rohde-schwarz.com>
Signed-off-by: Christian Gafert <christian.gafert@rohde-schwarz.com>
Co-developed-by: Max Ferger <max.ferger@rohde-schwarz.com>
Signed-off-by: Max Ferger <max.ferger@rohde-schwarz.com>
Signed-off-by: Van Giang Nguyen <vangiang.nguyen@rohde-schwarz.com>
Acked-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
VanGiang Nguyen 2024-08-09 06:21:42 +00:00 committed by Greg Kroah-Hartman
parent 41fbdd4524
commit ab205e1c38
1 changed files with 2 additions and 1 deletions
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kernel/padata.c
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@ -396,7 +396,8 @@ void padata_do_serial(struct padata_priv *padata)
/* Sort in ascending order of sequence number. */
list_for_each_prev(pos, &reorder->list) {
cur = list_entry(pos, struct padata_priv, list);
if (cur->seq_nr < padata->seq_nr)
/* Compare by difference to consider integer wrap around */
if ((signed int)(cur->seq_nr - padata->seq_nr) < 0)
break;
}
list_add(&padata->list, pos);