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/arch/powerpc/platforms/cell/spufs/coredump.c b/arch/powerpc/platforms/cell/spufs/coredump.c
index 84fb984..85c85eb 100644 (file)
--- a/arch/powerpc/platforms/cell/spufs/coredump.c
+++ b/arch/powerpc/platforms/cell/spufs/coredump.c
@@ -172,7 +172,7 @@ static int spufs_arch_write_note(struct spu_context *ctx, int i,
        if (rc < 0)
                goto out;
 
-       skip = roundup(cprm->file->f_pos - total + sz, 4) - cprm->file->f_pos;
+       skip = roundup(cprm->pos - total + sz, 4) - cprm->pos;
        if (!dump_skip(cprm, skip))
                goto Eio;
 out:

diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index e158b22..a7a2811 100644 (file)
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -2275,7 +2275,7 @@ static int elf_core_dump(struct coredump_params *cprm)
                goto end_coredump;
 
        /* Align to page */
-       if (!dump_skip(cprm, dataoff - cprm->file->f_pos))
+       if (!dump_skip(cprm, dataoff - cprm->pos))
                goto end_coredump;
 
        for (i = 0, vma = first_vma(current, gate_vma); vma != NULL;

diff --git a/fs/binfmt_elf_fdpic.c b/fs/binfmt_elf_fdpic.c
index 71ade0e..2035893 100644 (file)
--- a/fs/binfmt_elf_fdpic.c
+++ b/fs/binfmt_elf_fdpic.c
@@ -1787,7 +1787,7 @@ static int elf_fdpic_core_dump(struct coredump_params *cprm)
                                goto end_coredump;
        }
 
-       if (!dump_skip(cprm, dataoff - cprm->file->f_pos))
+       if (!dump_skip(cprm, dataoff - cprm->pos))
                goto end_coredump;
 
        if (!elf_fdpic_dump_segments(cprm))

diff --git a/fs/coredump.c b/fs/coredump.c
index 38a7ab8..281b768 100644 (file)
--- a/fs/coredump.c
+++ b/fs/coredump.c
@@ -794,6 +794,7 @@ int dump_emit(struct coredump_params *cprm, const void *addr, int nr)
                        return 0;
                file->f_pos = pos;
                cprm->written += n;
+               cprm->pos += n;
                nr -= n;
        }
        return 1;
@@ -808,6 +809,7 @@ int dump_skip(struct coredump_params *cprm, size_t nr)
                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 @@ EXPORT_SYMBOL(dump_skip);
 
 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;

diff --git a/include/linux/binfmts.h b/include/linux/binfmts.h
index 576e463..314b3ca 100644 (file)
--- a/include/linux/binfmts.h
+++ b/include/linux/binfmts.h
@@ -65,6 +65,7 @@ struct coredump_params {
        unsigned long limit;
        unsigned long mm_flags;
        loff_t written;
+       loff_t pos;
 };
 
 /*