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x86/xen/msr: Fix uninitialized variable 'err'

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xen_read_msr_safe() currently passes an uninitialized argument 'err' to
xen_do_read_msr(). But as xen_do_read_msr() may not set the argument,
xen_read_msr_safe() could return err with an unpredictable value.

To ensure correctness, initialize err to 0 (representing success)
in xen_read_msr_safe().

Do the same in xen_read_msr(), even err is not used after being passed
to xen_do_read_msr().

Closes: https://lore.kernel.org/xen-devel/aBxNI_Q0-MhtBSZG@stanley.mountain/
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Xin Li (Intel) <xin@zytor.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Juergen Gross <jgross@suse.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Link: https://lore.kernel.org/r/20250517165713.935384-1-xin@zytor.com
This commit is contained in:
Xin Li (Intel) 2025-05-17 09:57:12 -07:00 • committed by Ingo Molnar
parent 9220aa8a67
commit e95534e107
1 changed files with 2 additions and 2 deletions
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4
arch/x86/xen/enlighten_pv.c
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@ -1162,7 +1162,7 @@ static void xen_do_write_msr(u32 msr, u64 val, int *err)
static int xen_read_msr_safe(u32 msr, u64 *val)
{
int err;
int err = 0;
*val = xen_do_read_msr(msr, &err);
return err;
@ -1179,7 +1179,7 @@ static int xen_write_msr_safe(u32 msr, u64 val)
static u64 xen_read_msr(u32 msr)
{
int err;
int err = 0;
return xen_do_read_msr(msr, xen_msr_safe ? &err : NULL);
}