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
crc4.c
// SPDX-License-Identifier: GPL-2.0-only
/*
* crc4.c - simple crc-4 calculations.
*/
#include <linux/crc4.h>
#include <linux/module.h>
static const uint8_t crc4_tab[] = {
0x0, 0x7, 0xe, 0x9, 0xb, 0xc, 0x5, 0x2,
0x1, 0x6, 0xf, 0x8, 0xa, 0xd, 0x4, 0x3,
};
/**
* crc4 - calculate the 4-bit crc of a value.
* @c: starting crc4
* @x: value to checksum
* @bits: number of bits in @x to checksum
*
* Returns the crc4 value of @x, using polynomial 0b10111.
*
* The @x value is treated as left-aligned, and bits above @bits are ignored
* in the crc calculations.
*/
uint8_t crc4(uint8_t c, uint64_t x, int bits)
{
int i;
/* mask off anything above the top bit */
x &= (1ull << bits) - 1;
/* Align to 4-bits */
bits = (bits + 3) & ~0x3;
/* Calculate crc4 over four-bit nibbles, starting at the MSbit */
for (i = bits - 4; i >= 0; i -= 4)
c = crc4_tab[c ^ ((x >> i) & 0xf)];
return c;
}
EXPORT_SYMBOL_GPL(crc4);
MODULE_DESCRIPTION("CRC4 calculations");
MODULE_LICENSE("GPL");
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