Ivan.
diff -ur 2.3.18ac8/arch/alpha/kernel/alpha_ksyms.c linux/arch/alpha/kernel/alpha_ksyms.c
--- 2.3.18ac8/arch/alpha/kernel/alpha_ksyms.c Tue Aug 31 21:50:39 1999
+++ linux/arch/alpha/kernel/alpha_ksyms.c Tue Sep 21 13:12:59 1999
@@ -139,7 +139,7 @@
EXPORT_SYMBOL_NOVERS(__copy_user);
EXPORT_SYMBOL_NOVERS(__do_clear_user);
EXPORT_SYMBOL(__strncpy_from_user);
-EXPORT_SYMBOL(__strlen_user);
+EXPORT_SYMBOL(__strnlen_user);
/*
* The following are specially called from the semaphore assembly stubs.
diff -ur 2.3.18ac8/arch/alpha/lib/strlen_user.S linux/arch/alpha/lib/strlen_user.S
--- 2.3.18ac8/arch/alpha/lib/strlen_user.S Sun Apr 25 04:54:08 1999
+++ linux/arch/alpha/lib/strlen_user.S Tue Sep 21 13:12:11 1999
@@ -3,6 +3,13 @@
*
* Return the length of the string including the NUL terminator
* (strlen+1) or zero if an error occurred.
+ *
+ * In places where it is critical to limit the processing time,
+ * and the data is not trusted, strnlen_user() should be used.
+ * It will return a value greater than its second argument if
+ * that limit would be exceeded. This implementation is allowed
+ * to access memory beyond the limit, but will not cross a page
+ * boundary when doing so.
*/
#include <alpha/regdef.h>
@@ -27,6 +34,14 @@
.align 3
__strlen_user:
+ ldah a1, 32767(zero) # do not use plain strlen_user() for strings
+ # that might be almost 2 GB long; you should
+ # be using strnlen_user() instead
+
+ .globl __strnlen_user
+
+ .align 3
+__strnlen_user:
ldgp $29,0($27) # we do exceptions -- we need the gp.
.prologue 1
@@ -37,9 +52,17 @@
or t1, t0, t0
subq a0, 1, a0 # get our +1 for the return
cmpbge zero, t0, t1 # t1 <- bitmask: bit i == 1 <==> i-th byte == 0
+ subq a1, 7, t2
+ subq a0, v0, t0
bne t1, $found
-$loop: EX( ldq t0, 8(v0) )
+ addq t2, t0, t2
+ addq a1, 1, a1
+
+ .align 3
+$loop: ble t2, $limit
+ EX( ldq t0, 8(v0) )
+ subq t2, 8, t2
addq v0, 8, v0 # addr += 8
cmpbge zero, t0, t1
beq t1, $loop
@@ -59,6 +82,11 @@
nop # dual issue next two on ev4 and ev5
subq v0, a0, v0
$exception:
+ ret
+
+ .align 3 # currently redundant
+$limit:
+ subq a1, t2, v0
ret
.end __strlen_user
diff -ur 2.3.18ac8/include/asm-alpha/uaccess.h linux/include/asm-alpha/uaccess.h
--- 2.3.18ac8/include/asm-alpha/uaccess.h Fri Jul 30 00:37:22 1999
+++ linux/include/asm-alpha/uaccess.h Tue Sep 21 13:16:07 1999
@@ -487,6 +487,15 @@
return access_ok(VERIFY_READ,str,0) ? __strlen_user(str) : 0;
}
+/* Returns: 0 if exception before NUL or reaching the supplied limit (N),
+ * a value greater than N if the limit would be exceeded, else strlen. */
+extern long __strnlen_user(const char *, long);
+
+extern inline long strnlen_user(const char *str, long n)
+{
+ return access_ok(VERIFY_READ,str,0) ? __strnlen_user(str, n) : 0;
+}
+
/*
* About the exception table:
*
-
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