[PATCH v5 4/6] x86/insn-eval: Make 0 a valid RIP for insn_get_effective_ip()

Joerg Roedel
2021-06-14T13:53:54Z

From: Joerg Roedel <jroedel@suse.de>

In theory 0 is a valid value for the instruction pointer, so don't use
it as the error return value from insn_get_effective_ip().

Signed-off-by: Joerg Roedel <jroedel@suse.de>
---
arch/x86/lib/insn-eval.c | 14 +++++++-------
1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/arch/x86/lib/insn-eval.c b/arch/x86/lib/insn-eval.c
index a67afd74232c..4eecb9c7c6a0 100644
--- a/arch/x86/lib/insn-eval.c
+++ b/arch/x86/lib/insn-eval.c
@@ -1417,7 +1417,7 @@ void __user *insn_get_addr_ref(struct insn *insn, struct pt_regs *regs)
}
}

-static unsigned long insn_get_effective_ip(struct pt_regs *regs)
+static int insn_get_effective_ip(struct pt_regs *regs, unsigned long *ip)
{
unsigned long seg_base = 0;

@@ -1430,10 +1430,12 @@ static unsigned long insn_get_effective_ip(struct pt_regs *regs)
if (!user_64bit_mode(regs)) {
seg_base = insn_get_seg_base(regs, INAT_SEG_REG_CS);
if (seg_base == -1L)
- return 0;
+ return -EINVAL;
}

- return seg_base + regs->ip;
+ *ip = seg_base + regs->ip;
+
+ return 0;
}

/**
@@ -1455,8 +1457,7 @@ int insn_fetch_from_user(struct pt_regs *regs, unsigned char buf[MAX_INSN_SIZE])
unsigned long ip;
int not_copied;

- ip = insn_get_effective_ip(regs);
- if (!ip)
+ if (insn_get_effective_ip(regs, &ip))
return 0;

not_copied = copy_from_user(buf, (void __user *)ip, MAX_INSN_SIZE);
@@ -1484,8 +1485,7 @@ int insn_fetch_from_user_inatomic(struct pt_regs *regs, unsigned char buf[MAX_IN
unsigned long ip;
int not_copied;

- ip = insn_get_effective_ip(regs);
- if (!ip)
+ if (insn_get_effective_ip(regs, &ip))
return 0;

not_copied = __copy_from_user_inatomic(buf, (void __user *)ip, MAX_INSN_SIZE);
--
2.31.1