[05/10] binfmt_flat: use proper user space accessors with relocs processing code

Message ID 1468358862-11799-6-git-send-email-nicolas.pitre@linaro.org
State New
Headers show

Commit Message

Nicolas Pitre July 12, 2016, 9:27 p.m.
Relocs are fixed up in place in user space memory.  The appropriate
accessors are required for this code to work with an active MMU.

Only those architectures with trivial architecture-specific handlers are
covered by this patch. Incidentally, those NOMMU architectures that can
also have a MMU are amongst the trivial ones so it should be fine.
---
 arch/arm/include/asm/flat.h    |  5 +++--
 arch/m68k/include/asm/flat.h   |  5 +++--
 arch/sh/include/asm/flat.h     |  5 +++--
 arch/xtensa/include/asm/flat.h |  5 +++--
 fs/binfmt_flat.c               | 31 +++++++++++++++++++------------
 5 files changed, 31 insertions(+), 20 deletions(-)

-- 
2.7.4

Patch

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/arch/sh/include/asm/flat.h b/arch/sh/include/asm/flat.h
index 5d84df5e27..0f4f49ed6b 100644
--- a/arch/sh/include/asm/flat.h
+++ b/arch/sh/include/asm/flat.h
@@ -15,8 +15,9 @@ 
 #define	flat_argvp_envp_on_stack()		0
 #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)
 #define	flat_set_persistent(relval, p)		({ (void)p; 0; })
 
diff --git a/arch/xtensa/include/asm/flat.h b/arch/xtensa/include/asm/flat.h
index 94c44abf15..fffad219af 100644
--- a/arch/xtensa/include/asm/flat.h
+++ b/arch/xtensa/include/asm/flat.h
@@ -4,8 +4,9 @@ 
 #define flat_argvp_envp_on_stack()			0
 #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)
 #define flat_set_persistent(relval, p)			0
 
diff --git a/fs/binfmt_flat.c b/fs/binfmt_flat.c
index 9538901fe8..fc0ee3ed5d 100644
--- a/fs/binfmt_flat.c
+++ b/fs/binfmt_flat.c
@@ -438,7 +438,7 @@  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;
@@ -600,7 +600,7 @@  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;
@@ -625,7 +625,7 @@  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;
@@ -718,15 +718,20 @@  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;
 			}
 		}
 	}
@@ -743,19 +748,21 @@  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;
 			}