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[PATCH 08/10] binfmt_flat: update libraries' data segment pointer with userspace accessors

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This is needed on systems with a MMU.  This also gets rid of the
strangest C code I've seen lateli i.e. an integer indexed with a
pointer value within square brackets. That really looked backwards.

Signed-off-by: Nicolas Pitre <nico@linaro.org>
---
 fs/binfmt_flat.c | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/fs/binfmt_flat.c b/fs/binfmt_flat.c
index e981e66bb5..3221ed9d7c 100644
--- a/fs/binfmt_flat.c
+++ b/fs/binfmt_flat.c
@@ -902,12 +902,19 @@ static int load_flat_binary(struct linux_binprm * bprm)
 		return res;
 	
 	/* Update data segment pointers for all libraries */
-	for (i=0; i<MAX_SHARED_LIBS; i++)
-		if (libinfo.lib_list[i].loaded)
-			for (j=0; j<MAX_SHARED_LIBS; j++)
-				(-(j+1))[(unsigned long *)(libinfo.lib_list[i].start_data)] =
-					(libinfo.lib_list[j].loaded)?
-						libinfo.lib_list[j].start_data:UNLOADED_LIB;
+	for (i=0; i<MAX_SHARED_LIBS; i++) {
+		if (!libinfo.lib_list[i].loaded)
+			continue;
+		for (j=0; j<MAX_SHARED_LIBS; j++) {
+			unsigned long val = libinfo.lib_list[j].loaded ?
+				libinfo.lib_list[j].start_data : UNLOADED_LIB;
+			unsigned long __user *p = (unsigned long __user *)
+				libinfo.lib_list[i].start_data;
+			p -= j + 1;
+			if (put_user(val, p))
+				return -EFAULT;
+		}
+	}
 
 	install_exec_creds(bprm);
 
-- 
2.7.4

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[PATCH 00/10] allow BFLT executables on systems with a MMU Nicolas Pitre <nicolas.pitre@linaro.org> - 2016-07-12 23:50 +0200
  [PATCH  07/10] binfmt_flat: use clear_user() rather than memset() to clear .bss Nicolas Pitre <nicolas.pitre@linaro.org> - 2016-07-12 23:50 +0200
  [PATCH  09/10] binfmt_flat: add MMU-specific support Nicolas Pitre <nicolas.pitre@linaro.org> - 2016-07-12 23:50 +0200
  [PATCH  03/10] binfmt_flat: use generic transfer_args_to_stack() Nicolas Pitre <nicolas.pitre@linaro.org> - 2016-07-12 23:50 +0200
  [PATCH  05/10] binfmt_flat: use proper user space accessors with relocs processing code Nicolas Pitre <nicolas.pitre@linaro.org> - 2016-07-12 23:50 +0200
  [PATCH  01/10] binfmt_flat: assorted cleanups Nicolas Pitre <nicolas.pitre@linaro.org> - 2016-07-12 23:50 +0200
  [PATCH  10/10] binfmt_flat: allow compressed flat binary format to work on MMU systems Nicolas Pitre <nicolas.pitre@linaro.org> - 2016-07-12 23:50 +0200
  [PATCH  08/10] binfmt_flat: update libraries' data segment pointer with userspace accessors Nicolas Pitre <nicolas.pitre@linaro.org> - 2016-07-12 23:50 +0200
  [PATCH  06/10] binfmt_flat: use proper user space accessors with old relocs code Nicolas Pitre <nicolas.pitre@linaro.org> - 2016-07-12 23:50 +0200
  [PATCH  02/10] elf_fdpic_transfer_args_to_stack(): make it generic Nicolas Pitre <nicolas.pitre@linaro.org> - 2016-07-12 23:50 +0200
  [PATCH  04/10] binfmt_flat: clean up create_flat_tables() and stack accesses Nicolas Pitre <nicolas.pitre@linaro.org> - 2016-07-12 23:50 +0200

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