[RHEL6.8 Patch 3/3] vmcore: continue vmcore initialization if PT_NOTE is found empty

[Baoquan He <bhe@redhat.com>]

Resolves: bz1236437
https://bugzilla.redhat.com/show_bug.cgi?id=1236437

Brew build:
https://brewweb.devel.redhat.com/taskinfo?taskID=9499237

This is back ported from upstream. This commit relies on commit
"vmcore: prevent PT_NOTE p_memsz overflow during header update".

commit c4082f36fa3eeb5d4fadc50241b6e3a388561f80
Author: WANG Chao <chaowang@redhat.com>
Date:   Mon Apr 7 15:38:51 2014 -0700

    vmcore: continue vmcore initialization if PT_NOTE is found empty

    Currently when an empty PT_NOTE is detected, vmcore initialization
    fails.  It sounds too harsh.  Because PT_NOTE could be empty, for
    example, one offlined a cpu but never restarted kdump service, and after
    crash, PT_NOTE program header is there but no data contains.  It's
    better to warn about the empty PT_NOTE and continue to initialise
    vmcore.

    And ultimately the multiple PT_NOTE are merged into a single one, all
    empty PT_NOTE are discarded naturally during the merge.  So empty
    PT_NOTE is not visible to user space and vmcore is as good as expected.

    Signed-off-by: WANG Chao <chaowang@redhat.com>
    Cc: Vivek Goyal <vgoyal@redhat.com>
    Cc: HATAYAMA Daisuke <d.hatayama@jp.fujitsu.com>
    Cc: Greg Pearson <greg.pearson@hp.com>
    Cc: Baoquan He <bhe@redhat.com>
    Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
    Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Signed-off-by: Baoquan He <bhe@redhat.com>
---
 fs/proc/vmcore.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c
index 97c950b..ecc7604 100644
--- a/fs/proc/vmcore.c
+++ b/fs/proc/vmcore.c
@@ -260,7 +260,6 @@ static int __init merge_note_headers_elf64(char *elfptr, size_t *elfsz,
 		kfree(notes_section);
 		if (real_sz == 0) {
 			pr_warn("Warning: Zero PT_NOTE entries found\n");
-			return -EINVAL;
 		}
 	}
 
@@ -347,7 +346,6 @@ static int __init merge_note_headers_elf32(char *elfptr, size_t *elfsz,
 		kfree(notes_section);
 		if (real_sz == 0) {
 			pr_warn("Warning: Zero PT_NOTE entries found\n");
-			return -EINVAL;
 		}
 
 	}
-- 
2.1.0