linux-kernel - [PATCH] FDPIC: Fix the /proc/pid/stat representation of executable boundaries

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Message-ID: <20070322122919.31568.99690.stgit@warthog.cambridge.redhat.com>
Date:	Thu, 22 Mar 2007 12:29:19 +0000
From:	David Howells <dhowells@...hat.com>
To:	torvalds@...l.org, akpm@...l.org, rgetz@...ckfin.uclinux.org
Cc:	linux-kernel@...r.kernel.org, dhowells@...hat.com
Subject: [PATCH] FDPIC: Fix the /proc/pid/stat representation of executable
	boundaries

From: David Howells <dhowells@...hat.com>

Fix the /proc/pid/stat representation of executable boundaries.  It should show
the bounds of the executable, but instead shows the bounds of the loader.

Before the patch is applied, the bug can be seen by examining, say, inetd:

	# ps | grep inetd
	  610         root          0   S   /usr/sbin/inetd -i
	# cat /proc/610/maps
	c0bb0000-c0bba788 r-xs 00000000 00:0b 14582157  /lib/ld-uClibc-0.9.28.so
	c3180000-c31dede4 r-xs 00000000 00:0b 14582179  /lib/libuClibc-0.9.28.so
	c328c000-c328ea00 rw-p 00008000 00:0b 14582157  /lib/ld-uClibc-0.9.28.so
	c3290000-c329b6c0 rw-p 00000000 00:00 0
	c32a0000-c32c0000 rwxp 00000000 00:00 0
	c32d4000-c32d8000 rw-p 00000000 00:00 0
	c3394000-c3398000 rw-p 00000000 00:00 0
	c3458000-c345f464 r-xs 00000000 00:0b 16384612  /usr/sbin/inetd
	c3470000-c34748f8 rw-p 00004000 00:0b 16384612  /usr/sbin/inetd
	c34cc000-c34d0000 rw-p 00000000 00:00 0
	c34d4000-c34d8000 rw-p 00000000 00:00 0
	c34d8000-c34dc000 rw-p 00000000 00:00 0
	# cat /proc/610/stat
	610 (inetd) S 1 610 610 0 -1 256 0 0 0 0 0 8 0 0 19 0 1 0 94392000718
	950272 0 4294967295 3233480704 3233523592 3274440352 3274439976
 	3273467584 0 0 4096 90115 3221712796 0 0 17 0 0 0 0

The code boundaries are 3233480704 to 3233523592, which are:

	(gdb) p/x 3233480704
	$1 = 0xc0bb0000
	(gdb) p/x 3233523592
	$2 = 0xc0bba788

Which corresponds to this line in the maps file:

	c0bb0000-c0bba788 r-xs 00000000 00:0b 14582157  /lib/ld-uClibc-0.9.28.so

Which is wrong.  After the patch is applied, the maps file is pretty much
identical (there's some minor shuffling of the location of some of the
anonymous VMAs), but the stat file is now:

	# cat /proc/610/stat
	610 (inetd) S 1 610 610 0 -1 256 0 0 0 0 0 7 0 0 18 0 1 0 94392000722
	950272 0 4294967295 3276111872 3276141668 3274440352 3274439976
	3273467584 0 0 4096 90115 3221712796 0 0 17 0 0 0 0

The code boundaries are then 3276111872 to 3276141668, which are:

	(gdb) p/x 3276111872
	$1 = 0xc3458000
	(gdb) p/x 3276141668
	$2 = 0xc345f464

And these correspond to this line in the maps file instead:

	c3458000-c345f464 r-xs 00000000 00:0b 16384612  /usr/sbin/inetd

Which is now correct.

Signed-Off-By: David Howells <dhowells@...hat.com>
---

 fs/binfmt_elf_fdpic.c |   15 +++++++++++----
 1 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/fs/binfmt_elf_fdpic.c b/fs/binfmt_elf_fdpic.c
index 5810aa1..47d6d49 100644
--- a/fs/binfmt_elf_fdpic.c
+++ b/fs/binfmt_elf_fdpic.c
@@ -179,6 +179,8 @@ static int load_elf_fdpic_binary(struct linux_binprm *bprm,
 	int executable_stack;
 	int retval, i;
 
+	kdebug("____ LOAD %d ____", current->pid);
+
 	memset(&exec_params, 0, sizeof(exec_params));
 	memset(&interp_params, 0, sizeof(interp_params));
 
@@ -941,8 +943,11 @@ static int elf_fdpic_map_file_constdisp_on_uclinux(
 
 		if (mm) {
 			if (phdr->p_flags & PF_X) {
-				mm->start_code = seg->addr;
-				mm->end_code = seg->addr + phdr->p_memsz;
+				if (!mm->start_code) {
+					mm->start_code = seg->addr;
+					mm->end_code = seg->addr +
+						phdr->p_memsz;
+				}
 			} else if (!mm->start_data) {
 				mm->start_data = seg->addr;
 #ifndef CONFIG_MMU
@@ -1123,8 +1128,10 @@ static int elf_fdpic_map_file_by_direct_mmap(struct elf_fdpic_params *params,
 
 		if (mm) {
 			if (phdr->p_flags & PF_X) {
-				mm->start_code = maddr;
-				mm->end_code = maddr + phdr->p_memsz;
+				if (!mm->start_code) {
+					mm->start_code = maddr;
+					mm->end_code = maddr + phdr->p_memsz;
+				}
 			} else if (!mm->start_data) {
 				mm->start_data = maddr;
 				mm->end_data = maddr + phdr->p_memsz;

-
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