coredump: only charge written data against RLIMIT_CORE

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 <osandov@fb.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/fs/coredump.c b/fs/coredump.c
index 9db0c514438e38494e2ea78511f3645e84485535..492c2db25dc9bd654a3fb6931dc3bdc1162ac42d 100644 (file)
--- a/fs/coredump.c
+++ b/fs/coredump.c
@@ -782,7 +782,7 @@ 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())
@@ -791,6 +791,7 @@ int dump_emit(struct coredump_params *cprm, const void *addr, int nr)
                if (n <= 0)
                        return 0;
                file->f_pos = pos;
+               cprm->written += n;
                nr -= n;
        }
        return 1;
@@ -802,8 +803,6 @@ 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 39c6d6e1234e5398846a8d77feac9e111cf3e925..576e4639ca609e8bfb8686474406073937e912e9 100644 (file)
--- 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;
 };
 
 /*