tracing: uprobes: Re-enable $comm support for uprobe events (4dd537ac) · Commits · 戴 / test

Since commit ("tracing: probeevent: Introduce new argument fetching code") dropped the $comm support from uprobe events, this re-enables it. For $comm support, uses strlcpy() instead of strncpy_from_user() to copy current task's comm. Because it is in the kernel space, strncpy_from_user() always fails to copy the comm. This also uses strlen() instead of strnlen_user() to measure the length of the comm. Note that this uses -ECOMM as a token value to fetch the comm string. If the user-space pointer points -ECOMM, it will be translated to task->comm. Link: http://lkml.kernel.org/r/155723734162.9149.4042756162201097965.stgit@devnote2 Fixes: ("tracing: probeevent: Introduce new argument fetching code") Reported-by:

Andreas Ziegler <andreas.ziegler@fau.de> Acked-by:

Andreas Ziegler <andreas.ziegler@fau.de> Signed-off-by:

Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by:

Steven Rostedt (VMware) <rostedt@goodmis.org>

kernel/trace/trace_probe.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -124,6 +124,7 @@ struct fetch_insn {

		/* fetch + derefN + store + mod + end <= 16, this allows N=12, enough /
		#define FETCH_INSN_MAX 16
		#define FETCH_TOKEN_COMM (-ECOMM)

		/* Fetch type information table */
		struct fetch_type {

kernel/trace/trace_uprobe.c

+11 −2

Original line number	Diff line number	Diff line
		@@ -156,6 +156,9 @@ fetch_store_string(unsigned long addr, void dest, void base)
		if (unlikely(!maxlen))
		return -ENOMEM;

		if (addr == FETCH_TOKEN_COMM)
		ret = strlcpy(dst, current->comm, maxlen);
		else
		ret = strncpy_from_user(dst, src, maxlen);
		if (ret >= 0) {
		if (ret == maxlen)
		@@ -180,6 +183,9 @@ fetch_store_strlen(unsigned long addr)
		int len;
		void __user vaddr = (void __force __user ) addr;

		if (addr == FETCH_TOKEN_COMM)
		len = strlen(current->comm) + 1;
		else
		len = strnlen_user(vaddr, MAX_STRING_SIZE);

		return (len > MAX_STRING_SIZE) ? 0 : len;
		@@ -220,6 +226,9 @@ process_fetch_insn(struct fetch_insn code, struct pt_regs regs, void *dest,
		case FETCH_OP_IMM:
		val = code->immediate;
		break;
		case FETCH_OP_COMM:
		val = FETCH_TOKEN_COMM;
		break;
		case FETCH_OP_FOFFS:
		val = translate_user_vaddr(code->immediate);
		break;

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