This is a note to let you know that I've just added the patch titled
coredump: Ensure proper size of sparse core files
to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
coredump-ensure-proper-size-of-sparse-core-files.patch
and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From foo@baz Mon Jul 3 13:34:03 CEST 2017
From: Dave Kleikamp <dave.kleikamp@xxxxxxxxxx>
Date: Wed, 11 Jan 2017 13:25:00 -0600
Subject: coredump: Ensure proper size of sparse core files
From: Dave Kleikamp <dave.kleikamp@xxxxxxxxxx>
[ Upstream commit 4d22c75d4c7b5c5f4bd31054f09103ee490878fd ]
If the last section of a core file ends with an unmapped or zero page,
the size of the file does not correspond with the last dump_skip() call.
gdb complains that the file is truncated and can be confusing to users.
After all of the vma sections are written, make sure that the file size
is no smaller than the current file position.
This problem can be demonstrated with gdb's bigcore testcase on the
sparc architecture.
Signed-off-by: Dave Kleikamp <dave.kleikamp@xxxxxxxxxx>
Cc: Alexander Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: linux-fsdevel@xxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/binfmt_elf.c | 1 +
fs/coredump.c | 18 ++++++++++++++++++
include/linux/coredump.h | 1 +
3 files changed, 20 insertions(+)
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -2295,6 +2295,7 @@ static int elf_core_dump(struct coredump
goto end_coredump;
}
}
+ dump_truncate(cprm);
if (!elf_core_write_extra_data(cprm))
goto end_coredump;
--- a/fs/coredump.c
+++ b/fs/coredump.c
@@ -810,3 +810,21 @@ int dump_align(struct coredump_params *c
return mod ? dump_skip(cprm, align - mod) : 1;
}
EXPORT_SYMBOL(dump_align);
+
+/*
+ * Ensures that file size is big enough to contain the current file
+ * postion. This prevents gdb from complaining about a truncated file
+ * if the last "write" to the file was dump_skip.
+ */
+void dump_truncate(struct coredump_params *cprm)
+{
+ struct file *file = cprm->file;
+ loff_t offset;
+
+ if (file->f_op->llseek && file->f_op->llseek != no_llseek) {
+ offset = file->f_op->llseek(file, 0, SEEK_CUR);
+ if (i_size_read(file->f_mapping->host) < offset)
+ do_truncate(file->f_path.dentry, offset, 0, file);
+ }
+}
+EXPORT_SYMBOL(dump_truncate);
--- a/include/linux/coredump.h
+++ b/include/linux/coredump.h
@@ -14,6 +14,7 @@ struct coredump_params;
extern int dump_skip(struct coredump_params *cprm, size_t nr);
extern int dump_emit(struct coredump_params *cprm, const void *addr, int nr);
extern int dump_align(struct coredump_params *cprm, int align);
+extern void dump_truncate(struct coredump_params *cprm);
#ifdef CONFIG_COREDUMP
extern void do_coredump(const siginfo_t *siginfo);
#else
Patches currently in stable-queue which might be from dave.kleikamp@xxxxxxxxxx are
queue-4.4/coredump-ensure-proper-size-of-sparse-core-files.patch