[PATCH 5/7] binfmt_elf_fdpic: remove the set_fs(KERNEL_DS) in elf_fdpic_core_dump

Christoph Hellwig
2020-04-21T15:42:46Z

There is no logic in elf_fdpic_core_dump itself, or in the various arch
helpers called from it which use uaccess routines on kernel pointers
except for the file writes thate are nicely encapsulated by using
__kernel_write in dump_emit.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
fs/binfmt_elf_fdpic.c | 31 ++++++++++++-------------------
1 file changed, 12 insertions(+), 19 deletions(-)

diff --git a/fs/binfmt_elf_fdpic.c b/fs/binfmt_elf_fdpic.c
index 240f66663543..c62c17a5c34a 100644
--- a/fs/binfmt_elf_fdpic.c
+++ b/fs/binfmt_elf_fdpic.c
@@ -1549,7 +1549,6 @@ static int elf_fdpic_core_dump(struct coredump_params *cprm)
{
#define NUM_NOTES 6
int has_dumped = 0;
- mm_segment_t fs;
int segs;
int i;
struct vm_area_struct *vma;
@@ -1678,9 +1677,6 @@ static int elf_fdpic_core_dump(struct coredump_params *cprm)
"LINUX", ELF_CORE_XFPREG_TYPE, sizeof(*xfpu), xfpu);
#endif

- fs = get_fs();
- set_fs(KERNEL_DS);
-
offset += sizeof(*elf); /* Elf header */
offset += segs * sizeof(struct elf_phdr); /* Program headers */

@@ -1695,7 +1691,7 @@ static int elf_fdpic_core_dump(struct coredump_params *cprm)

phdr4note = kmalloc(sizeof(*phdr4note), GFP_KERNEL);
if (!phdr4note)
- goto end_coredump;
+ goto cleanup;

fill_elf_note_phdr(phdr4note, sz, offset);
offset += sz;
@@ -1711,17 +1707,17 @@ static int elf_fdpic_core_dump(struct coredump_params *cprm)
if (e_phnum == PN_XNUM) {
shdr4extnum = kmalloc(sizeof(*shdr4extnum), GFP_KERNEL);
if (!shdr4extnum)
- goto end_coredump;
+ goto cleanup;
fill_extnum_info(elf, shdr4extnum, e_shoff, segs);
}

offset = dataoff;

if (!dump_emit(cprm, elf, sizeof(*elf)))
- goto end_coredump;
+ goto cleanup;

if (!dump_emit(cprm, phdr4note, sizeof(*phdr4note)))
- goto end_coredump;
+ goto cleanup;

/* write program headers for segments dump */
for (vma = current->mm->mmap; vma; vma = vma->vm_next) {
@@ -1745,16 +1741,16 @@ static int elf_fdpic_core_dump(struct coredump_params *cprm)
phdr.p_align = ELF_EXEC_PAGESIZE;

if (!dump_emit(cprm, &phdr, sizeof(phdr)))
- goto end_coredump;
+ goto cleanup;
}

if (!elf_core_write_extra_phdrs(cprm, offset))
- goto end_coredump;
+ goto cleanup;

/* write out the notes section */
for (i = 0; i < numnote; i++)
if (!writenote(notes + i, cprm))
- goto end_coredump;
+ goto cleanup;

/* write out the thread status notes section */
list_for_each(t, &thread_list) {
@@ -1763,21 +1759,21 @@ static int elf_fdpic_core_dump(struct coredump_params *cprm)

for (i = 0; i < tmp->num_notes; i++)
if (!writenote(&tmp->notes[i], cprm))
- goto end_coredump;
+ goto cleanup;
}

if (!dump_skip(cprm, dataoff - cprm->pos))
- goto end_coredump;
+ goto cleanup;

if (!elf_fdpic_dump_segments(cprm))
- goto end_coredump;
+ goto cleanup;

if (!elf_core_write_extra_data(cprm))
- goto end_coredump;
+ goto cleanup;

if (e_phnum == PN_XNUM) {
if (!dump_emit(cprm, shdr4extnum, sizeof(*shdr4extnum)))
- goto end_coredump;
+ goto cleanup;
}

if (cprm->file->f_pos != offset) {
@@ -1787,9 +1783,6 @@ static int elf_fdpic_core_dump(struct coredump_params *cprm)
cprm->file->f_pos, offset);
}

-end_coredump:
- set_fs(fs);
-
cleanup:
while (!list_empty(&thread_list)) {
struct list_head *tmp = thread_list.next;
--
2.26.1