linux-kernel - [GIT pull] core fixes for 4.14

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Date:   Sun, 17 Sep 2017 11:36:16 +0200 (CEST)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
cc:     LKML <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...nel.org>,
        "H. Peter Anvin" <hpa@...or.com>
Subject: [GIT pull] core fixes for 4.14

Linus,

please pull the latest core-urgent-for-linus git tree from:

   git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git core-urgent-for-linus

This update contains:

  - A fix for a user space regression in /proc/$PID/stat

  - A couple of objtool fixes:

    - Plug a memory leak

    - Avoid accessing empty sections which upsets certain binutil versions
    
    - Prevent corrupting the obj file when section sizes did not change

Thanks,

	tglx

------------------>
John Ogness (1):
      fs/proc: Report eip/esp in /prod/PID/stat for coredumping

Josh Poimboeuf (1):
      objtool: Fix object file corruption

Martin Kepplinger (1):
      objtool: Fix memory leak in elf_create_rela_section()

Petr Vandrovec (1):
      objtool: Do not retrieve data from empty sections


 fs/proc/array.c     |  9 +++++++++
 tools/objtool/elf.c | 33 ++++++++++++++++++++-------------
 2 files changed, 29 insertions(+), 13 deletions(-)

diff --git a/fs/proc/array.c b/fs/proc/array.c
index 88c355574aa0..525157ca25cb 100644
--- a/fs/proc/array.c
+++ b/fs/proc/array.c
@@ -62,6 +62,7 @@
 #include <linux/mman.h>
 #include <linux/sched/mm.h>
 #include <linux/sched/numa_balancing.h>
+#include <linux/sched/task_stack.h>
 #include <linux/sched/task.h>
 #include <linux/sched/cputime.h>
 #include <linux/proc_fs.h>
@@ -421,7 +422,15 @@ static int do_task_stat(struct seq_file *m, struct pid_namespace *ns,
 		 * esp and eip are intentionally zeroed out.  There is no
 		 * non-racy way to read them without freezing the task.
 		 * Programs that need reliable values can use ptrace(2).
+		 *
+		 * The only exception is if the task is core dumping because
+		 * a program is not able to use ptrace(2) in that case. It is
+		 * safe because the task has stopped executing permanently.
 		 */
+		if (permitted && (task->flags & PF_DUMPCORE)) {
+			eip = KSTK_EIP(task);
+			esp = KSTK_ESP(task);
+		}
 	}
 
 	get_task_comm(tcomm, task);
diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index 6e9f980a7d26..24460155c82c 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -175,19 +175,20 @@ static int read_sections(struct elf *elf)
 			return -1;
 		}
 
-		sec->data = elf_getdata(s, NULL);
-		if (!sec->data) {
-			WARN_ELF("elf_getdata");
-			return -1;
-		}
-
-		if (sec->data->d_off != 0 ||
-		    sec->data->d_size != sec->sh.sh_size) {
-			WARN("unexpected data attributes for %s", sec->name);
-			return -1;
+		if (sec->sh.sh_size != 0) {
+			sec->data = elf_getdata(s, NULL);
+			if (!sec->data) {
+				WARN_ELF("elf_getdata");
+				return -1;
+			}
+			if (sec->data->d_off != 0 ||
+			    sec->data->d_size != sec->sh.sh_size) {
+				WARN("unexpected data attributes for %s",
+				     sec->name);
+				return -1;
+			}
 		}
-
-		sec->len = sec->data->d_size;
+		sec->len = sec->sh.sh_size;
 	}
 
 	/* sanity check, one more call to elf_nextscn() should return NULL */
@@ -508,6 +509,7 @@ struct section *elf_create_rela_section(struct elf *elf, struct section *base)
 	strcat(relaname, base->name);
 
 	sec = elf_create_section(elf, relaname, sizeof(GElf_Rela), 0);
+	free(relaname);
 	if (!sec)
 		return NULL;
 
@@ -561,6 +563,7 @@ int elf_write(struct elf *elf)
 	struct section *sec;
 	Elf_Scn *s;
 
+	/* Update section headers for changed sections: */
 	list_for_each_entry(sec, &elf->sections, list) {
 		if (sec->changed) {
 			s = elf_getscn(elf->elf, sec->idx);
@@ -568,13 +571,17 @@ int elf_write(struct elf *elf)
 				WARN_ELF("elf_getscn");
 				return -1;
 			}
-			if (!gelf_update_shdr (s, &sec->sh)) {
+			if (!gelf_update_shdr(s, &sec->sh)) {
 				WARN_ELF("gelf_update_shdr");
 				return -1;
 			}
 		}
 	}
 
+	/* Make sure the new section header entries get updated properly. */
+	elf_flagelf(elf->elf, ELF_C_SET, ELF_F_DIRTY);
+
+	/* Write all changes to the file. */
 	if (elf_update(elf->elf, ELF_C_WRITE) < 0) {
 		WARN_ELF("elf_update");
 		return -1;