coredump: fix dumping through pipes
The offset in the core file used to be tracked with ->written field of
the coredump_params structure. The field was retired in favour of
file->f_pos.
However, ->f_pos is not maintained for pipes which leads to breakage.
Restore explicit tracking of the offset in coredump_params. Introduce
->pos field for this purpose since ->written was already reused.
Fixes: a00839395103 ("get rid of coredump_params->written").
Reported-by: Zbigniew Jędrzejewski-Szmek <zbyszek@in.waw.pl>
Signed-off-by: Mateusz Guzik <mguzik@redhat.com>
Reviewed-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 38a7ab8..281b768 100644
--- a/fs/coredump.c
+++ b/fs/coredump.c
@@ -794,6 +794,7 @@
return 0;
file->f_pos = pos;
cprm->written += n;
+ cprm->pos += n;
nr -= n;
}
return 1;
@@ -808,6 +809,7 @@
if (dump_interrupted() ||
file->f_op->llseek(file, nr, SEEK_CUR) < 0)
return 0;
+ cprm->pos += nr;
return 1;
} else {
while (nr > PAGE_SIZE) {
@@ -822,7 +824,7 @@
int dump_align(struct coredump_params *cprm, int align)
{
- unsigned mod = cprm->file->f_pos & (align - 1);
+ unsigned mod = cprm->pos & (align - 1);
if (align & (align - 1))
return 0;
return mod ? dump_skip(cprm, align - mod) : 1;