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Date: Wed, 20 Jul 2016 00:20:19 -0400
From: Nicolas Pitre <nicolas.pitre@...aro.org>
To: linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Cc: Alexander Viro <viro@...iv.linux.org.uk>,
David Howells <dhowells@...hat.com>,
Greg Ungerer <gerg@...ux-m68k.org>
Subject: [PATCH v3 07/12] binfmt_flat: use proper user space accessors with relocs processing code
Relocs are fixed up in place in user space memory. The appropriate
accessors are required for this code to work with an active MMU.
The architecture specific handlers for ARM and M68K are also
covered. SuperH and Xtensa are left out as they doesn't implement
__get_user_unaligned() and __put_user_unaligned() yet. The other
architectures that use BFLT don't have any MMU.
Signed-off-by: Nicolas Pitre <nico@...aro.org>
Reviewed-by: Greg Ungerer <gerg@...ux-m68k.org>
---
arch/arm/include/asm/flat.h | 5 +++--
arch/m68k/include/asm/flat.h | 5 +++--
fs/binfmt_flat.c | 31 +++++++++++++++++++------------
3 files changed, 25 insertions(+), 16 deletions(-)
diff --git a/arch/arm/include/asm/flat.h b/arch/arm/include/asm/flat.h
index e847d23351..acf1d14b89 100644
--- a/arch/arm/include/asm/flat.h
+++ b/arch/arm/include/asm/flat.h
@@ -8,8 +8,9 @@
#define flat_argvp_envp_on_stack() 1
#define flat_old_ram_flag(flags) (flags)
#define flat_reloc_valid(reloc, size) ((reloc) <= (size))
-#define flat_get_addr_from_rp(rp, relval, flags, persistent) ((void)persistent,get_unaligned(rp))
-#define flat_put_addr_at_rp(rp, val, relval) put_unaligned(val,rp)
+#define flat_get_addr_from_rp(rp, relval, flags, persistent) \
+ ({ unsigned long __val; __get_user_unaligned(__val, rp); __val; })
+#define flat_put_addr_at_rp(rp, val, relval) __put_user_unaligned(val, rp)
#define flat_get_relocate_addr(rel) (rel)
#define flat_set_persistent(relval, p) 0
diff --git a/arch/m68k/include/asm/flat.h b/arch/m68k/include/asm/flat.h
index f9454b89a5..f3f592d03e 100644
--- a/arch/m68k/include/asm/flat.h
+++ b/arch/m68k/include/asm/flat.h
@@ -8,8 +8,9 @@
#define flat_argvp_envp_on_stack() 1
#define flat_old_ram_flag(flags) (flags)
#define flat_reloc_valid(reloc, size) ((reloc) <= (size))
-#define flat_get_addr_from_rp(rp, relval, flags, p) get_unaligned(rp)
-#define flat_put_addr_at_rp(rp, val, relval) put_unaligned(val,rp)
+#define flat_get_addr_from_rp(rp, relval, flags, p) \
+ ({ unsigned long __val; __get_user_unaligned(__val, rp); __val; })
+#define flat_put_addr_at_rp(rp, val, relval) __put_user_unaligned(val, rp)
#define flat_get_relocate_addr(rel) (rel)
static inline int flat_set_persistent(unsigned long relval,
diff --git a/fs/binfmt_flat.c b/fs/binfmt_flat.c
index 90a10d7149..34f815540e 100644
--- a/fs/binfmt_flat.c
+++ b/fs/binfmt_flat.c
@@ -423,7 +423,7 @@ static int load_flat_file(struct linux_binprm * bprm,
unsigned long textpos, datapos, realdatastart;
unsigned long text_len, data_len, bss_len, stack_len, full_data, flags;
unsigned long len, memp, memp_size, extra, rlim;
- unsigned long *reloc, *rp;
+ unsigned long __user *reloc, *rp;
struct inode *inode;
int i, rev, relocs;
loff_t fpos;
@@ -595,7 +595,7 @@ static int load_flat_file(struct linux_binprm * bprm,
goto err;
}
- reloc = (unsigned long *)
+ reloc = (unsigned long __user *)
(datapos + (ntohl(hdr->reloc_start) - text_len));
memp = realdatastart;
memp_size = len;
@@ -620,7 +620,7 @@ static int load_flat_file(struct linux_binprm * bprm,
MAX_SHARED_LIBS * sizeof(unsigned long),
FLAT_DATA_ALIGN);
- reloc = (unsigned long *)
+ reloc = (unsigned long __user *)
(datapos + (ntohl(hdr->reloc_start) - text_len));
memp = textpos;
memp_size = len;
@@ -713,15 +713,20 @@ static int load_flat_file(struct linux_binprm * bprm,
* image.
*/
if (flags & FLAT_FLAG_GOTPIC) {
- for (rp = (unsigned long *)datapos; *rp != 0xffffffff; rp++) {
- unsigned long addr;
- if (*rp) {
- addr = calc_reloc(*rp, libinfo, id, 0);
+ for (rp = (unsigned long __user *)datapos; ; rp++) {
+ unsigned long addr, rp_val;
+ if (get_user(rp_val, rp))
+ return -EFAULT;
+ if (rp_val == 0xffffffff)
+ break;
+ if (rp_val) {
+ addr = calc_reloc(rp_val, libinfo, id, 0);
if (addr == RELOC_FAILED) {
ret = -ENOEXEC;
goto err;
}
- *rp = addr;
+ if (put_user(addr, rp))
+ return -EFAULT;
}
}
}
@@ -738,19 +743,21 @@ static int load_flat_file(struct linux_binprm * bprm,
* __start to address 4 so that is okay).
*/
if (rev > OLD_FLAT_VERSION) {
- unsigned long persistent = 0;
+ unsigned long __maybe_unused persistent = 0;
for (i=0; i < relocs; i++) {
unsigned long addr, relval;
/* Get the address of the pointer to be
relocated (of course, the address has to be
relocated first). */
- relval = ntohl(reloc[i]);
+ if (get_user(relval, reloc + i))
+ return -EFAULT;
+ relval = ntohl(relval);
if (flat_set_persistent (relval, &persistent))
continue;
addr = flat_get_relocate_addr(relval);
- rp = (unsigned long *) calc_reloc(addr, libinfo, id, 1);
- if (rp == (unsigned long *)RELOC_FAILED) {
+ rp = (unsigned long __user *)calc_reloc(addr, libinfo, id, 1);
+ if (rp == (unsigned long __user *)RELOC_FAILED) {
ret = -ENOEXEC;
goto err;
}
--
2.7.4
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