[patch 4/7] BSD Secure Levels: memory alloc failure check

[Michael Halcrow <mhalcrow@us.ibm.com>]

This is the fourth in a series of seven patches to the BSD Secure
Levels LSM.  It adds a check for a memory allocation failure
condition.  Thanks to Vesa-Matti J Kari for pointing out this problem.

Signed off by: Michael Halcrow <mhalcrow@us.ibm.com>

Index: linux-2.6.12-rc4-mm2-seclvl/security/seclvl.c
===================================================================
--- linux-2.6.12-rc4-mm2-seclvl.orig/security/seclvl.c	2005-05-16 16:28:19.000000000 -0500
+++ linux-2.6.12-rc4-mm2-seclvl/security/seclvl.c	2005-05-16 16:28:29.000000000 -0500
@@ -310,7 +310,7 @@
 static int
 plaintext_to_sha1(unsigned char *hash, const char *plaintext, int len)
 {
-	char *pgVirtAddr;
+	char *pg_virt_addr;
 	struct crypto_tfm *tfm;
 	struct scatterlist sg[1];
 	if (len > PAGE_SIZE) {
@@ -327,16 +327,20 @@
 	}
 	// Just get a new page; don't play around with page boundaries
 	// and scatterlists.
-	pgVirtAddr = (char *)__get_free_page(GFP_KERNEL);
-	sg[0].page = virt_to_page(pgVirtAddr);
+	pg_virt_addr = (char *)__get_free_page(GFP_KERNEL);
+	if (!pg_virt_addr) {
+		seclvl_printk(0, KERN_ERR "%s: Out of memory\n", __FUNCTION__);
+		return -ENOMEM;
+	}
+	sg[0].page = virt_to_page(pg_virt_addr);
 	sg[0].offset = 0;
 	sg[0].length = len;
-	strncpy(pgVirtAddr, plaintext, len);
+	strncpy(pg_virt_addr, plaintext, len);
 	crypto_digest_init(tfm);
 	crypto_digest_update(tfm, sg, 1);
 	crypto_digest_final(tfm, hash);
 	crypto_free_tfm(tfm);
-	free_page((unsigned long)pgVirtAddr);
+	free_page((unsigned long)pg_virt_addr);
 	return 0;
 }