Revision 7ff57e98fb78ad94edafbdc7435f2d745e9e6bb5 authored by Fabio M. De Francesco on 23 February 2022, 10:02:52 UTC, committed by Jakub Kicinski on 24 February 2022, 17:09:33 UTC
smc_pnetid_by_table_ib() uses read_lock() and then it calls smc_pnet_apply_ib()
which, in turn, calls mutex_lock(&smc_ib_devices.mutex).
read_lock() disables preemption. Therefore, the code acquires a mutex while in
atomic context and it leads to a SAC bug.
Fix this bug by replacing the rwlock with a mutex.
Reported-and-tested-by: syzbot+4f322a6d84e991c38775@syzkaller.appspotmail.com
Fixes: 64e28b52c7a6 ("net/smc: add pnet table namespace support")
Confirmed-by: Tony Lu <tonylu@linux.alibaba.com>
Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
Acked-by: Karsten Graul <kgraul@linux.ibm.com>
Link: https://lore.kernel.org/r/20220223100252.22562-1-fmdefrancesco@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
1 parent e13ad14
memcat_p.c
// SPDX-License-Identifier: GPL-2.0
#include <linux/slab.h>
/*
* Merge two NULL-terminated pointer arrays into a newly allocated
* array, which is also NULL-terminated. Nomenclature is inspired by
* memset_p() and memcat() found elsewhere in the kernel source tree.
*/
void **__memcat_p(void **a, void **b)
{
void **p = a, **new;
int nr;
/* count the elements in both arrays */
for (nr = 0, p = a; *p; nr++, p++)
;
for (p = b; *p; nr++, p++)
;
/* one for the NULL-terminator */
nr++;
new = kmalloc_array(nr, sizeof(void *), GFP_KERNEL);
if (!new)
return NULL;
/* nr -> last index; p points to NULL in b[] */
for (nr--; nr >= 0; nr--, p = p == b ? &a[nr] : p - 1)
new[nr] = *p;
return new;
}
EXPORT_SYMBOL_GPL(__memcat_p);
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