Hi.
In arch/ia64/kernel/trace.c, ftrace_make_nop() apparently can call
ftrace_modify_code() with second parameter (old_code) set to NULL,
which ftrace_make_nop can dereference. I have attached an appended an
untested patch which I think should cause ftrace_modify_code to avoid
the pointer dereference when old_code is null.
I am not an Itanium developer or user but just want to submit what I
think is a fix for a bug that cppcheck pointed me to. I have not even
tried to compile with this patch. So, please feel free to replace
this with a patch more to your liking.
It has been a long time since I tried to submit a Linux kernel patch,
so I am not up to date on the latest process requirements. I hereby
release my copyright interest in this patch to the public domain and
state that, to the best of my knowledge, my contribution does not add
anyone else's copyright interests or other intellectual property.
This contribution should not be taken to imply my agreement,
disagreement or making of any "pledge" with respect to any "code of
conduct" or other terms. If you need me to make some other statement
or do something else, please just let me know.
Thanks in advance for considering this patch.
Adam Richter
diff --git a/arch/ia64/kernel/ftrace.c b/arch/ia64/kernel/ftrace.c
index 7fc8c961b1f7..98085dcbf20a 100644
--- a/arch/ia64/kernel/ftrace.c
+++ b/arch/ia64/kernel/ftrace.c
@@ -114,7 +114,8 @@ ftrace_modify_code(unsigned long ip, unsigned char
*old_code,
return -EFAULT;
/* Make sure it is what we expect it to be */
- if (memcmp(replaced, old_code, MCOUNT_INSN_SIZE) != 0)
+ if (old_code != NULL &&
+ memcmp(replaced, old_code, MCOUNT_INSN_SIZE) != 0)
return -EINVAL;
skip_check:
diff --git a/arch/ia64/kernel/ftrace.c b/arch/ia64/kernel/ftrace.c index 7fc8c961b1f7..98085dcbf20a 100644 --- a/arch/ia64/kernel/ftrace.c +++ b/arch/ia64/kernel/ftrace.c @@ -114,7 +114,8 @@ ftrace_modify_code(unsigned long ip, unsigned char *old_code, return -EFAULT; /* Make sure it is what we expect it to be */ - if (memcmp(replaced, old_code, MCOUNT_INSN_SIZE) != 0) + if (old_code != NULL && + memcmp(replaced, old_code, MCOUNT_INSN_SIZE) != 0) return -EINVAL; skip_check:
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