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Date:      Fri, 23 Nov 2018 22:36:56 +0000 (UTC)
From:      Maxim Sobolev <sobomax@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r340857 - head/stand/common
Message-ID:  <201811232236.wANMau1c016899@repo.freebsd.org>
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Author: sobomax
Date: Fri Nov 23 22:36:56 2018
New Revision: 340857
URL: https://svnweb.freebsd.org/changeset/base/340857

Log:
  Nuke out buffer overflow safety marker code, it duplicates similar code in
  the malloc()/free() as well as having potential of softening the handling
  in case error is detected down to a mere warning as compared to hard panic
  in free().
  
  Submitted by:	tsoome
  Differential Revision:	https://reviews.freebsd.org/D18299

Modified:
  head/stand/common/bcache.c

Modified: head/stand/common/bcache.c
==============================================================================
--- head/stand/common/bcache.c	Fri Nov 23 22:24:59 2018	(r340856)
+++ head/stand/common/bcache.c	Fri Nov 23 22:36:56 2018	(r340857)
@@ -86,7 +86,6 @@ static u_int bcache_rablks;
 	((bc)->bcache_ctl[BHASH((bc), (blkno))].bc_blkno != (blkno))
 #define	BCACHE_READAHEAD	256
 #define	BCACHE_MINREADAHEAD	32
-#define	BCACHE_MARKER		0xdeadbeef
 
 static void	bcache_invalidate(struct bcache *bc, daddr_t blkno);
 static void	bcache_insert(struct bcache *bc, daddr_t blkno);
@@ -123,7 +122,6 @@ bcache_allocate(void)
     u_int i;
     struct bcache *bc = malloc(sizeof (struct bcache));
     int disks = bcache_numdev;
-    uint32_t *marker;
 
     if (disks == 0)
 	disks = 1;	/* safe guard */
@@ -142,8 +140,7 @@ bcache_allocate(void)
 
     bc->bcache_nblks = bcache_total_nblks >> i;
     bcache_unit_nblks = bc->bcache_nblks;
-    bc->bcache_data = malloc(bc->bcache_nblks * bcache_blksize +
-	sizeof(uint32_t));
+    bc->bcache_data = malloc(bc->bcache_nblks * bcache_blksize);
     if (bc->bcache_data == NULL) {
 	/* dont error out yet. fall back to 32 blocks and try again */
 	bc->bcache_nblks = 32;
@@ -158,9 +155,6 @@ bcache_allocate(void)
 	errno = ENOMEM;
 	return (NULL);
     }
-    /* Insert cache end marker. */
-    marker = (uint32_t *)(bc->bcache_data + bc->bcache_nblks * bcache_blksize);
-    *marker = BCACHE_MARKER;
 
     /* Flush the cache */
     for (i = 0; i < bc->bcache_nblks; i++) {
@@ -222,15 +216,12 @@ read_strategy(void *devdata, int rw, daddr_t blk, size
     int				result;
     daddr_t			p_blk;
     caddr_t			p_buf;
-    uint32_t			*marker;
 
     if (bc == NULL) {
 	errno = ENODEV;
 	return (-1);
     }
 
-    marker = (uint32_t *)(bc->bcache_data + bc->bcache_nblks * bcache_blksize);
-
     if (rsize != NULL)
 	*rsize = 0;
 
@@ -348,12 +339,6 @@ read_strategy(void *devdata, int rw, daddr_t blk, size
     if (size != 0) {
 	bcopy(bc->bcache_data + (bcache_blksize * BHASH(bc, blk)), buf, size);
 	result = 0;
-    }
-
-    if (*marker != BCACHE_MARKER) {
-	printf("BUG: bcache corruption detected: nblks: %zu p_blk: %lu, "
-	    "p_size: %zu, ra: %zu\n", bc->bcache_nblks,
-	    (long unsigned)BHASH(bc, p_blk), p_size, ra);
     }
 
  done:

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