Commit e0d7b0a2 authored Jan 15, 2019 by Colin Ian King Committed by Greg Kroah-Hartman Feb 27, 2019

atm: he: fix sign-extension overflow on large shift



[ Upstream commit cb12d72b27a6f41325ae23a11033cf5fedfa1b97 ]

Shifting the 1 by exp by an int can lead to sign-extension overlow when
exp is 31 since 1 is an signed int and sign-extending this result to an
unsigned long long will set the upper 32 bits.  Fix this by shifting an
unsigned long.

Detected by cppcheck:
(warning) Shifting signed 32-bit value by 31 bits is undefined behaviour

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>

parent 22b304bf

drivers/atm/he.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -717,7 +717,7 @@ static int he_init_cs_block_rcm(struct he_dev *he_dev)
		instead of '/ 512', use '>> 9' to prevent a call
		to divdu3 on x86 platforms
		*/
		rate_cps = (unsigned long long) (1 << exp) * (man + 512) >> 9;
		rate_cps = (unsigned long long) (1UL << exp) * (man + 512) >> 9;

		if (rate_cps < 10)
		rate_cps = 10; /* 2.2.1 minimum payload rate is 10 cps */