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authorMasami Hiramatsu <mhiramat@kernel.org>2021-01-27 18:37:51 +0300
committerSteven Rostedt (VMware) <rostedt@goodmis.org>2021-01-29 23:39:48 +0300
commit97c753e62e6c31a404183898d950d8c08d752dbd (patch)
tree392edaa43558a756376b727f2c4d7f22b447db71 /kernel/kprobes.c
parentda7f84cdf02fd5f66864041f45018b328911b722 (diff)
downloadlinux-97c753e62e6c31a404183898d950d8c08d752dbd.tar.xz
tracing/kprobe: Fix to support kretprobe events on unloaded modules
Fix kprobe_on_func_entry() returns error code instead of false so that register_kretprobe() can return an appropriate error code. append_trace_kprobe() expects the kprobe registration returns -ENOENT when the target symbol is not found, and it checks whether the target module is unloaded or not. If the target module doesn't exist, it defers to probe the target symbol until the module is loaded. However, since register_kretprobe() returns -EINVAL instead of -ENOENT in that case, it always fail on putting the kretprobe event on unloaded modules. e.g. Kprobe event: /sys/kernel/debug/tracing # echo p xfs:xfs_end_io >> kprobe_events [ 16.515574] trace_kprobe: This probe might be able to register after target module is loaded. Continue. Kretprobe event: (p -> r) /sys/kernel/debug/tracing # echo r xfs:xfs_end_io >> kprobe_events sh: write error: Invalid argument /sys/kernel/debug/tracing # cat error_log [ 41.122514] trace_kprobe: error: Failed to register probe event Command: r xfs:xfs_end_io ^ To fix this bug, change kprobe_on_func_entry() to detect symbol lookup failure and return -ENOENT in that case. Otherwise it returns -EINVAL or 0 (succeeded, given address is on the entry). Link: https://lkml.kernel.org/r/161176187132.1067016.8118042342894378981.stgit@devnote2 Cc: stable@vger.kernel.org Fixes: 59158ec4aef7 ("tracing/kprobes: Check the probe on unloaded module correctly") Reported-by: Jianlin Lv <Jianlin.Lv@arm.com> Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Diffstat (limited to 'kernel/kprobes.c')
-rw-r--r--kernel/kprobes.c34
1 files changed, 25 insertions, 9 deletions
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index f7fb5d135930..1a5bc321e0a5 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -1954,29 +1954,45 @@ bool __weak arch_kprobe_on_func_entry(unsigned long offset)
return !offset;
}
-bool kprobe_on_func_entry(kprobe_opcode_t *addr, const char *sym, unsigned long offset)
+/**
+ * kprobe_on_func_entry() -- check whether given address is function entry
+ * @addr: Target address
+ * @sym: Target symbol name
+ * @offset: The offset from the symbol or the address
+ *
+ * This checks whether the given @addr+@offset or @sym+@offset is on the
+ * function entry address or not.
+ * This returns 0 if it is the function entry, or -EINVAL if it is not.
+ * And also it returns -ENOENT if it fails the symbol or address lookup.
+ * Caller must pass @addr or @sym (either one must be NULL), or this
+ * returns -EINVAL.
+ */
+int kprobe_on_func_entry(kprobe_opcode_t *addr, const char *sym, unsigned long offset)
{
kprobe_opcode_t *kp_addr = _kprobe_addr(addr, sym, offset);
if (IS_ERR(kp_addr))
- return false;
+ return PTR_ERR(kp_addr);
- if (!kallsyms_lookup_size_offset((unsigned long)kp_addr, NULL, &offset) ||
- !arch_kprobe_on_func_entry(offset))
- return false;
+ if (!kallsyms_lookup_size_offset((unsigned long)kp_addr, NULL, &offset))
+ return -ENOENT;
- return true;
+ if (!arch_kprobe_on_func_entry(offset))
+ return -EINVAL;
+
+ return 0;
}
int register_kretprobe(struct kretprobe *rp)
{
- int ret = 0;
+ int ret;
struct kretprobe_instance *inst;
int i;
void *addr;
- if (!kprobe_on_func_entry(rp->kp.addr, rp->kp.symbol_name, rp->kp.offset))
- return -EINVAL;
+ ret = kprobe_on_func_entry(rp->kp.addr, rp->kp.symbol_name, rp->kp.offset);
+ if (ret)
+ return ret;
if (kretprobe_blacklist_size) {
addr = kprobe_addr(&rp->kp);