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

Message ID 1468358862-11799-9-git-send-email-nicolas.pitre@linaro.org (mailing list archive)
State New, archived
Headers show

Commit Message

Nicolas Pitre July 12, 2016, 9:27 p.m. UTC 
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(-)
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Patch

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);