6.6-stable review patch. If anyone has any objections, please let me know.
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From: VanGiang Nguyen vangiang.nguyen@rohde-schwarz.com
commit 9a22b2812393d93d84358a760c347c21939029a6 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: bfde23ce200e ("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 --- kernel/padata.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
--- a/kernel/padata.c +++ b/kernel/padata.c @@ -404,7 +404,8 @@ void padata_do_serial(struct padata_priv /* 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);