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    Subject[PATCH -tip 03/13] kprobes: Return -ENOENT if probe point doesn't exist
    Date
    Return -ENOENT if probe point doesn't exist, but still returns
    -EINVAL if both of kprobe->addr and kprobe->symbol_name are
    specified or both are not specified.

    Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
    Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
    Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
    Cc: "David S. Miller" <davem@davemloft.net>
    ---

    kernel/kprobes.c | 33 +++++++++++++++++++++++----------
    1 files changed, 23 insertions(+), 10 deletions(-)

    diff --git a/kernel/kprobes.c b/kernel/kprobes.c
    index 7798181..b30fd54 100644
    --- a/kernel/kprobes.c
    +++ b/kernel/kprobes.c
    @@ -1255,19 +1255,29 @@ static int __kprobes in_kprobes_functions(unsigned long addr)
    /*
    * If we have a symbol_name argument, look it up and add the offset field
    * to it. This way, we can specify a relative address to a symbol.
    + * This returns encoded errors if it fails to look up symbol or invalid
    + * combination of parameters.
    */
    static kprobe_opcode_t __kprobes *kprobe_addr(struct kprobe *p)
    {
    kprobe_opcode_t *addr = p->addr;
    +
    + if ((p->symbol_name && p->addr) ||
    + (!p->symbol_name && !p->addr))
    + goto invalid;
    +
    if (p->symbol_name) {
    - if (addr)
    - return NULL;
    kprobe_lookup_name(p->symbol_name, addr);
    + if (!addr)
    + return ERR_PTR(-ENOENT);
    }

    - if (!addr)
    - return NULL;
    - return (kprobe_opcode_t *)(((char *)addr) + p->offset);
    + addr = (kprobe_opcode_t *)(((char *)addr) + p->offset);
    + if (addr)
    + return addr;
    +
    +invalid:
    + return ERR_PTR(-EINVAL);
    }

    /* Check passed kprobe is valid and return kprobe in kprobe_table. */
    @@ -1311,8 +1321,8 @@ int __kprobes register_kprobe(struct kprobe *p)
    kprobe_opcode_t *addr;

    addr = kprobe_addr(p);
    - if (!addr)
    - return -EINVAL;
    + if (IS_ERR(addr))
    + return PTR_ERR(addr);
    p->addr = addr;

    ret = check_kprobe_rereg(p);
    @@ -1335,6 +1345,8 @@ int __kprobes register_kprobe(struct kprobe *p)
    */
    probed_mod = __module_text_address((unsigned long) p->addr);
    if (probed_mod) {
    + /* Return -ENOENT if fail. */
    + ret = -ENOENT;
    /*
    * We must hold a refcount of the probed module while updating
    * its code to prohibit unexpected unloading.
    @@ -1351,6 +1363,7 @@ int __kprobes register_kprobe(struct kprobe *p)
    module_put(probed_mod);
    goto fail_with_jump_label;
    }
    + /* ret will be updated by following code */
    }
    preempt_enable();
    jump_label_unlock();
    @@ -1399,7 +1412,7 @@ out:
    fail_with_jump_label:
    preempt_enable();
    jump_label_unlock();
    - return -EINVAL;
    + return ret;
    }
    EXPORT_SYMBOL_GPL(register_kprobe);

    @@ -1686,8 +1699,8 @@ int __kprobes register_kretprobe(struct kretprobe *rp)

    if (kretprobe_blacklist_size) {
    addr = kprobe_addr(&rp->kp);
    - if (!addr)
    - return -EINVAL;
    + if (IS_ERR(addr))
    + return PTR_ERR(addr);

    for (i = 0; kretprobe_blacklist[i].name != NULL; i++) {
    if (kretprobe_blacklist[i].addr == addr)


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