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tracing: uprobes: Re-enable $comm support for uprobe events

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Since commit 533059281e ("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: 533059281e ("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>
This commit is contained in:
Masami Hiramatsu 2019-05-07 22:55:41 +09:00 committed by Steven Rostedt (VMware)
parent 9e298e8604
commit 4dd537aca2
2 changed files with 12 additions and 2 deletions
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1
kernel/trace/trace_probe.h
View File

@ -124,6 +124,7 @@ struct fetch_insn {
/* fetch + deref*N + 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 {

13
kernel/trace/trace_uprobe.c
View File

@ -156,7 +156,10 @@ fetch_store_string(unsigned long addr, void *dest, void *base)
if (unlikely(!maxlen))
return -ENOMEM;
ret = strncpy_from_user(dst, src, maxlen);
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)
dst[ret - 1] = '\0';
@ -180,7 +183,10 @@ fetch_store_strlen(unsigned long addr)
int len;
void __user *vaddr = (void __force __user *) addr;
len = strnlen_user(vaddr, MAX_STRING_SIZE);
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;