[PATCH v2 06/10] binfmt_flat: use proper user space accessors with old relocs code

From: Nicolas Pitre
Date: Sun Jul 17 2016 - 23:32:35 EST


Signed-off-by: Nicolas Pitre <nico@xxxxxxxxxx>
---
fs/binfmt_flat.c | 28 ++++++++++++++++++----------
1 file changed, 18 insertions(+), 10 deletions(-)

diff --git a/fs/binfmt_flat.c b/fs/binfmt_flat.c
index fc0ee3ed5d..c85f8f1239 100644
--- a/fs/binfmt_flat.c
+++ b/fs/binfmt_flat.c
@@ -394,38 +394,41 @@ static void old_reloc(unsigned long rl)
static const char *segment[] = { "TEXT", "DATA", "BSS", "*UNKNOWN*" };
#endif
flat_v2_reloc_t r;
- unsigned long *ptr;
+ unsigned long __user *ptr;
+ unsigned long val;

r.value = rl;
#if defined(CONFIG_COLDFIRE)
- ptr = (unsigned long *) (current->mm->start_code + r.reloc.offset);
+ ptr = (unsigned long __user *)(current->mm->start_code + r.reloc.offset);
#else
- ptr = (unsigned long *) (current->mm->start_data + r.reloc.offset);
+ ptr = (unsigned long __user *)(current->mm->start_data + r.reloc.offset);
#endif
+ __get_user(val, ptr);

#ifdef DEBUG
printk("Relocation of variable at DATASEG+%x "
"(address %p, currently %lx) into segment %s\n",
- r.reloc.offset, ptr, *ptr, segment[r.reloc.type]);
+ r.reloc.offset, ptr, val, segment[r.reloc.type]);
#endif

switch (r.reloc.type) {
case OLD_FLAT_RELOC_TYPE_TEXT:
- *ptr += current->mm->start_code;
+ val += current->mm->start_code;
break;
case OLD_FLAT_RELOC_TYPE_DATA:
- *ptr += current->mm->start_data;
+ val += current->mm->start_data;
break;
case OLD_FLAT_RELOC_TYPE_BSS:
- *ptr += current->mm->end_data;
+ val += current->mm->end_data;
break;
default:
printk("BINFMT_FLAT: Unknown relocation type=%x\n", r.reloc.type);
break;
}
+ __put_user(val, ptr);

#ifdef DEBUG
- printk("Relocation became %lx\n", *ptr);
+ printk("Relocation became %lx\n", val);
#endif
}

@@ -788,8 +791,13 @@ static int load_flat_file(struct linux_binprm * bprm,
}
}
} else {
- for (i=0; i < relocs; i++)
- old_reloc(ntohl(reloc[i]));
+ for (i=0; i < relocs; i++) {
+ unsigned long relval;
+ if (get_user(relval, reloc + i))
+ return -EFAULT;
+ relval = ntohl(relval);
+ old_reloc(relval);
+ }
}

flush_icache_range(start_code, end_code);
--
2.7.4