[2/2] coredump: only charge written data against RLIMIT_CORE

Commit Message

Omar Sandoval Feb. 19, 2016, 12:32 a.m. UTC

From: Omar Sandoval <[e-mail]>

Commit 9b56d54380ad ("dump_skip(): dump_seek() replacement taking
coredump_params") introduced a regression with regard to RLIMIT_CORE.
Previously, when a core dump was sparse, only the data that was actually
written out would count against the limit. Now, the sparse ranges are
also included, which leads to truncated core dumps when the actual disk
usage is still well below the limit. Restore the old behavior by only
counting what gets emitted and ignoring what gets skipped.

Signed-off-by: Omar Sandoval <[e-mail]>
---
 fs/coredump.c           | 5 ++---
 include/linux/binfmts.h | 1 +
 2 files changed, 3 insertions(+), 3 deletions(-)

Patch

diff --git a/fs/coredump.c b/fs/coredump.c
index dc9268bbd61b..8272bd511603 100644
--- a/fs/coredump.c
+++ b/fs/coredump.c
@@ -760,7 +760,7 @@  int dump_emit(struct coredump_params *cprm, const void *addr, int nr)
 	struct file *file = cprm->file;
 	loff_t pos = file->f_pos;
 	ssize_t n;
-	if (pos + nr > cprm->limit)
+	if (cprm->written + nr > cprm->limit)
 		return 0;
 	while (nr) {
 		if (dump_interrupted())
@@ -769,6 +769,7 @@  int dump_emit(struct coredump_params *cprm, const void *addr, int nr)
 		if (n <= 0)
 			return 0;
 		file->f_pos = pos;
+		cprm->written += nr;
 		nr -= n;
 	}
 	return 1;
@@ -780,8 +781,6 @@  int dump_skip(struct coredump_params *cprm, size_t nr)
 	static char zeroes[PAGE_SIZE];
 	struct file *file = cprm->file;
 	if (file->f_op->llseek && file->f_op->llseek != no_llseek) {
-		if (file->f_pos + nr > cprm->limit)
-			return 0;
 		if (dump_interrupted() ||
 		    file->f_op->llseek(file, nr, SEEK_CUR) < 0)
 			return 0;
diff --git a/include/linux/binfmts.h b/include/linux/binfmts.h
index 39c6d6e1234e..576e4639ca60 100644
--- a/include/linux/binfmts.h
+++ b/include/linux/binfmts.h
@@ -64,6 +64,7 @@  struct coredump_params {
 	struct file *file;
 	unsigned long limit;
 	unsigned long mm_flags;
+	loff_t written;
 };
 
 /*