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

Christoph Hellwig
2020-05-05T10:13:44Z

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 | 21 +++++++--------------
1 file changed, 7 insertions(+), 14 deletions(-)

diff --git a/fs/binfmt_elf_fdpic.c b/fs/binfmt_elf_fdpic.c
index 240f666635437..d9501a86cec97 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;
@@ -1589,31 +1588,31 @@ static int elf_fdpic_core_dump(struct coredump_params *cprm)
/* alloc memory for large data structures: too large to be on stack */
elf = kmalloc(sizeof(*elf), GFP_KERNEL);
if (!elf)
- goto cleanup;
+ goto end_coredump;
prstatus = kzalloc(sizeof(*prstatus), GFP_KERNEL);
if (!prstatus)
- goto cleanup;
+ goto end_coredump;
psinfo = kmalloc(sizeof(*psinfo), GFP_KERNEL);
if (!psinfo)
- goto cleanup;
+ goto end_coredump;
notes = kmalloc_array(NUM_NOTES, sizeof(struct memelfnote),
GFP_KERNEL);
if (!notes)
- goto cleanup;
+ goto end_coredump;
fpu = kmalloc(sizeof(*fpu), GFP_KERNEL);
if (!fpu)
- goto cleanup;
+ goto end_coredump;
#ifdef ELF_CORE_COPY_XFPREGS
xfpu = kmalloc(sizeof(*xfpu), GFP_KERNEL);
if (!xfpu)
- goto cleanup;
+ goto end_coredump;
#endif

for (ct = current->mm->core_state->dumper.next;
ct; ct = ct->next) {
tmp = kzalloc(sizeof(*tmp), GFP_KERNEL);
if (!tmp)
- goto cleanup;
+ goto end_coredump;

tmp->thread = ct->task;
list_add(&tmp->list, &thread_list);
@@ -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 */

@@ -1788,9 +1784,6 @@ static int elf_fdpic_core_dump(struct coredump_params *cprm)
}

end_coredump:
- set_fs(fs);
-
-cleanup:
while (!list_empty(&thread_list)) {
struct list_head *tmp = thread_list.next;
list_del(tmp);
--
2.26.2