From: Colin Ian King Date: Tue, 5 Jun 2018 16:51:07 +0000 (+0100) Subject: ipmi_si: fix potential integer overflow on large shift X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=97a103e6b584442cd848887ed8d47be2410b7e09;p=linux.git ipmi_si: fix potential integer overflow on large shift Shifting unsigned char b by an int type can lead to sign-extension overflow. For example, if b is 0xff and the shift is 24, then top bit is sign-extended so the final value passed to writeq has all the upper 32 bits set. Fix this by casting b to a 64 bit unsigned before the shift. Detected by CoverityScan, CID#1465246 ("Unintended sign extension") Signed-off-by: Colin Ian King Signed-off-by: Corey Minyard --- diff --git a/drivers/char/ipmi/ipmi_si_mem_io.c b/drivers/char/ipmi/ipmi_si_mem_io.c index 1b869d530884c..fd0ec8d6bf0ef 100644 --- a/drivers/char/ipmi/ipmi_si_mem_io.c +++ b/drivers/char/ipmi/ipmi_si_mem_io.c @@ -51,7 +51,7 @@ static unsigned char mem_inq(const struct si_sm_io *io, unsigned int offset) static void mem_outq(const struct si_sm_io *io, unsigned int offset, unsigned char b) { - writeq(b << io->regshift, (io->addr)+(offset * io->regspacing)); + writeq((u64)b << io->regshift, (io->addr)+(offset * io->regspacing)); } #endif