Messages in this thread Patch in this message | | | From | Sasha Levin <> | Subject | [PATCH AUTOSEL 4.4 14/16] atm: he: fix sign-extension overflow on large shift | Date | Tue, 12 Feb 2019 21:41:10 -0500 |
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From: Colin Ian King <colin.king@canonical.com>
[ 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> --- drivers/atm/he.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/atm/he.c b/drivers/atm/he.c index 0f5cb37636bc..010581e8bee0 100644 --- a/drivers/atm/he.c +++ b/drivers/atm/he.c @@ -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 */ -- 2.19.1
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