Avoid collect2 calling signal unsafe functions and/or unlink, with uninitialized memory (for gcc-9 branch)

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  • Avoid collect2 calling signal unsafe functions and/or unlink, with uninitialized memory (for gcc-9 branch)
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Commit Message

Bernd Edlinger Feb. 21, 2020, 4:07 p.m.
Hi,

this fixes the signal handler calling signal unsafe vfprintf and/or passing
uninitialized memory to unlink in signal handler.

This time it is the patch for the gcc-9 branch.

The difference to the gcc-8 branch is in tool_cleanup:
The variable that suppress the vfprintf is verbose = false;
not debug = false, to match the different logic in maybe_unlink.


Bootstrapped and reg-tested with x86_64-pc-linux-gnu.
Is it OK for the gcc-9 branch?


Thanks
Bernd.

Comments

Richard Biener Feb. 24, 2020, 11:32 a.m. | #1
On Fri, 21 Feb 2020, Bernd Edlinger wrote:

> Hi,

> 

> this fixes the signal handler calling signal unsafe vfprintf and/or passing

> uninitialized memory to unlink in signal handler.

> 

> This time it is the patch for the gcc-9 branch.

> 

> The difference to the gcc-8 branch is in tool_cleanup:

> The variable that suppress the vfprintf is verbose = false;

> not debug = false, to match the different logic in maybe_unlink.

> 

> 

> Bootstrapped and reg-tested with x86_64-pc-linux-gnu.

> Is it OK for the gcc-9 branch?


OK.

Richard.

Patch

From d52ac2c0394f0432e183511f8a6d4f96b49f88a5 Mon Sep 17 00:00:00 2001
From: Bernd Edlinger <bernd.edlinger@hotmail.de>
Date: Mon, 17 Feb 2020 17:40:07 +0100
Subject: [PATCH] Avoid collect2 calling signal unsafe functions and/or unlink
 with uninitialized memory

2020-02-20  Bernd Edlinger  <bernd.edlinger@hotmail.de>

	* collect2.c (tool_cleanup): Avoid calling not signal-safe
	functions.
	(maybe_run_lto_and_relink): Avoid possible signal handler
	access to unintialzed memory (lto_o_files).
---
 gcc/collect2.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/gcc/collect2.c b/gcc/collect2.c
index eb84f84..8f092e7 100644
--- a/gcc/collect2.c
+++ b/gcc/collect2.c
@@ -384,6 +384,10 @@  static void scan_prog_file (const char *, scanpass, scanfilter);
 void
 tool_cleanup (bool from_signal)
 {
+  /* maybe_unlink may call notice, which is not signal safe.  */
+  if (from_signal)
+    verbose = false;
+
   if (c_file != 0 && c_file[0])
     maybe_unlink (c_file);
 
@@ -743,7 +747,10 @@  maybe_run_lto_and_relink (char **lto_ld_argv, char **object_lst,
 	      ++num_files;
 	  }
 
-	lto_o_files = XNEWVEC (char *, num_files + 1);
+	/* signal handler may access uninitialized memory
+	   and delete whatever it points to, if lto_o_files
+	   is not allocated with calloc.  */
+	lto_o_files = XCNEWVEC (char *, num_files + 1);
 	lto_o_files[num_files] = NULL;
 	start = XOBFINISH (&temporary_obstack, char *);
 	for (i = 0; i < num_files; ++i)
-- 
2.7.4