Return an error from __copy_instruction and use printk to
give us more productive message, since this is just an error
case which we can handle it and also the BUG_ON() never
tell us why and what happened,
This is related to the below bug-report.
https://bugzilla.redhat.com/show_bug.cgi?id=910649
Note, this patch is for help to analyze what happened.
Signed-off-by: Masami Hiramatsu <[email protected]>
Cc: Frank Ch. Eigler <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: "H. Peter Anvin" <[email protected]>
Cc: Steven Rostedt <[email protected]>
---
arch/x86/kernel/kprobes/core.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c
index 7bfe318..a86f83d 100644
--- a/arch/x86/kernel/kprobes/core.c
+++ b/arch/x86/kernel/kprobes/core.c
@@ -353,7 +353,11 @@ int __kprobes __copy_instruction(u8 *dest, u8 *src)
* have given.
*/
newdisp = (u8 *) src + (s64) insn.displacement.value - (u8 *) dest;
- BUG_ON((s64) (s32) newdisp != newdisp); /* Sanity check. */
+ if ((s64) (s32) newdisp != newdisp) {
+ pr_err("Kprobes error: new displacement is not fit in s32 (%llx)\n", newdisp);
+ pr_err("\tSrc: %p, Dest: %p, old disp: %x\n", src, dest, insn.displacement.value);
+ return 0;
+ }
disp = (u8 *) dest + insn_offset_displacement(&insn);
*(s32 *) disp = (s32) newdisp;
}
Commit-ID: 8101376dc5f42bd93b36d4ab210b44503d0ec11f
Gitweb: http://git.kernel.org/tip/8101376dc5f42bd93b36d4ab210b44503d0ec11f
Author: Masami Hiramatsu <[email protected]>
AuthorDate: Thu, 4 Apr 2013 19:42:30 +0900
Committer: Ingo Molnar <[email protected]>
CommitDate: Mon, 8 Apr 2013 17:28:34 +0200
kprobes/x86: Just return error for sanity check failure instead of using BUG_ON
Return an error from __copy_instruction() and use printk() to
give us a more productive message, since this is just an error
case which we can handle and also the BUG_ON() never tells us
why and what happened.
This is related to the following bug-report:
https://bugzilla.redhat.com/show_bug.cgi?id=910649
Signed-off-by: Masami Hiramatsu <[email protected]>
Cc: Frank Ch. Eigler <[email protected]>
Cc: Steven Rostedt <[email protected]>
Cc: [email protected]
Link: http://lkml.kernel.org/r/20130404104230.22862.85242.stgit@mhiramat-M0-7522
Signed-off-by: Ingo Molnar <[email protected]>
---
arch/x86/kernel/kprobes/core.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c
index 7bfe318..9895a9a 100644
--- a/arch/x86/kernel/kprobes/core.c
+++ b/arch/x86/kernel/kprobes/core.c
@@ -353,7 +353,11 @@ int __kprobes __copy_instruction(u8 *dest, u8 *src)
* have given.
*/
newdisp = (u8 *) src + (s64) insn.displacement.value - (u8 *) dest;
- BUG_ON((s64) (s32) newdisp != newdisp); /* Sanity check. */
+ if ((s64) (s32) newdisp != newdisp) {
+ pr_err("Kprobes error: new displacement does not fit into s32 (%llx)\n", newdisp);
+ pr_err("\tSrc: %p, Dest: %p, old disp: %x\n", src, dest, insn.displacement.value);
+ return 0;
+ }
disp = (u8 *) dest + insn_offset_displacement(&insn);
*(s32 *) disp = (s32) newdisp;
}