linux-kernel - [PATCH] alpha: exception table sorting

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [day] [month] [year] [list]

Message-ID: <20090424144327.GB32087@jurassic.park.msu.ru>
Date:	Fri, 24 Apr 2009 18:43:27 +0400
From:	Ivan Kokshaysky <ink@...assic.park.msu.ru>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Richard Henderson <rth@...ddle.net>, linux-kernel@...r.kernel.org
Subject: [PATCH] alpha: exception table sorting

Exception fixups for sections other than .text (like one in
futex_init()) break the natural ordering of fixup entries,
so sorting is required.

Without that the result of the exception table search depends
on phase of the moon.

Signed-off-by: Ivan Kokshaysky <ink@...assic.park.msu.ru>
---
 arch/alpha/include/asm/uaccess.h |    2 +
 arch/alpha/mm/extable.c          |   40 +++++++++++++++++++++++++++++++++++++-
 2 files changed, 41 insertions(+), 1 deletions(-)

diff --git a/arch/alpha/include/asm/uaccess.h b/arch/alpha/include/asm/uaccess.h
index 163f305..b49ec2f 100644
--- a/arch/alpha/include/asm/uaccess.h
+++ b/arch/alpha/include/asm/uaccess.h
@@ -507,5 +507,7 @@ struct exception_table_entry
 	(pc) + (_fixup)->fixup.bits.nextinsn;			\
 })
 
+#define ARCH_HAS_SORT_EXTABLE
+#define ARCH_HAS_SEARCH_EXTABLE
 
 #endif /* __ALPHA_UACCESS_H */
diff --git a/arch/alpha/mm/extable.c b/arch/alpha/mm/extable.c
index dc7aeda..62dc379 100644
--- a/arch/alpha/mm/extable.c
+++ b/arch/alpha/mm/extable.c
@@ -3,11 +3,49 @@
  */
 
 #include <linux/module.h>
+#include <linux/sort.h>
 #include <asm/uaccess.h>
 
+static inline unsigned long ex_to_addr(const struct exception_table_entry *x)
+{
+	return (unsigned long)&x->insn + x->insn;
+}
+
+static void swap_ex(void *a, void *b, int size)
+{
+	struct exception_table_entry *ex_a = a, *ex_b = b;
+	unsigned long addr_a = ex_to_addr(ex_a), addr_b = ex_to_addr(ex_b);
+	unsigned int t = ex_a->fixup.unit;
+
+	ex_a->fixup.unit = ex_b->fixup.unit;
+	ex_b->fixup.unit = t;
+	ex_a->insn = (int)(addr_b - (unsigned long)&ex_a->insn);
+	ex_b->insn = (int)(addr_a - (unsigned long)&ex_b->insn);
+}
+
+/*
+ * The exception table needs to be sorted so that the binary
+ * search that we use to find entries in it works properly.
+ * This is used both for the kernel exception table and for
+ * the exception tables of modules that get loaded.
+ */
+static int cmp_ex(const void *a, const void *b)
+{
+	const struct exception_table_entry *x = a, *y = b;
+
+	/* avoid overflow */
+	if (ex_to_addr(x) > ex_to_addr(y))
+		return 1;
+	if (ex_to_addr(x) < ex_to_addr(y))
+		return -1;
+	return 0;
+}
+
 void sort_extable(struct exception_table_entry *start,
 		  struct exception_table_entry *finish)
 {
+	sort(start, finish - start, sizeof(struct exception_table_entry),
+	     cmp_ex, swap_ex);
 }
 
 const struct exception_table_entry *
@@ -20,7 +58,7 @@ search_extable(const struct exception_table_entry *first,
 		unsigned long mid_value;
 
 		mid = (last - first) / 2 + first;
-		mid_value = (unsigned long)&mid->insn + mid->insn;
+		mid_value = ex_to_addr(mid);
                 if (mid_value == value)
                         return mid;
                 else if (mid_value < value)
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/