[PATCH v3 3/7] kprobes: validate the symbol name length
From: Naveen N. Rao <hidden>
Date: 2017-04-19 12:51:37
Also in:
lkml
Subsystem:
kprobes, the rest, tracing · Maintainers:
Naveen N Rao, "David S. Miller", Masami Hiramatsu, Linus Torvalds, Steven Rostedt
When a kprobe is being registered, we use the symbol_name field to lookup the address where the probe should be placed. Since this is a user-provided field, let's ensure that the length of the string is within expected limits. Signed-off-by: Naveen N. Rao <redacted> --- include/linux/kprobes.h | 1 + kernel/kprobes.c | 24 ++++++++++++++++++++++++ kernel/trace/trace_kprobe.c | 4 ++++ 3 files changed, 29 insertions(+)
diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h
index 1f82a3db00b1..4ee10fef5135 100644
--- a/include/linux/kprobes.h
+++ b/include/linux/kprobes.h@@ -405,6 +405,7 @@ int disable_kprobe(struct kprobe *kp); int enable_kprobe(struct kprobe *kp); void dump_kprobe(struct kprobe *kp); +bool is_valid_kprobe_symbol_name(const char *name); #else /* !CONFIG_KPROBES: */
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 6a128f3a7ed1..bb86681c8a10 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c@@ -1382,6 +1382,28 @@ bool within_kprobe_blacklist(unsigned long addr) return false; } +bool is_valid_kprobe_symbol_name(const char *name) +{ + size_t sym_len; + char *s; + + s = strchr(name, ':'); + if (s) { + sym_len = strnlen(s+1, KSYM_NAME_LEN); + if (sym_len <= 0 || sym_len >= KSYM_NAME_LEN) + return false; + sym_len = (size_t)(s - name); + if (sym_len <= 0 || sym_len >= MODULE_NAME_LEN) + return false; + } else { + sym_len = strnlen(name, MODULE_NAME_LEN); + if (sym_len <= 0 || sym_len >= MODULE_NAME_LEN) + return false; + } + + return true; +} + /* * 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.
@@ -1397,6 +1419,8 @@ static kprobe_opcode_t *kprobe_addr(struct kprobe *p) goto invalid; if (p->symbol_name) { + if (!is_valid_kprobe_symbol_name(p->symbol_name)) + return ERR_PTR(-EINVAL); addr = kprobe_lookup_name(p->symbol_name, p->offset); if (!addr) return ERR_PTR(-ENOENT);
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 5f688cc724f0..bf73e5f31128 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c@@ -704,6 +704,10 @@ static int create_trace_kprobe(int argc, char **argv) pr_info("Return probe must be used without offset.\n"); return -EINVAL; } + if (!is_valid_kprobe_symbol_name(symbol)) { + pr_info("Symbol name is too long.\n"); + return -EINVAL; + } } argc -= 2; argv += 2;
--
2.12.1