xfs: fix memcpy fortify errors in EFI log format copying

Starting in 6.1, CONFIG_FORTIFY_SOURCE checks the length parameter of
memcpy.  Since we're already fixing problems with BUI item copying, we
should fix it everything else.

An extra difficulty here is that the ef[id]_extents arrays are declared
as single-element arrays.  This is not the convention for flex arrays in
the modern kernel, and it causes all manner of problems with static
checking tools, since they often cannot tell the difference between a
single element array and a flex array.

So for starters, change those array[1] declarations to array[]
declarations to signal that they are proper flex arrays and adjust all
the "size-1" expressions to fit the new declaration style.

Next, refactor the xfs_efi_copy_format function to handle the copying of
the head and the flex array members separately.  While we're at it, fix
a minor validation deficiency in the recovery function.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Allison Henderson <allison.henderson@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>

4 files changed, 36 insertions, 22 deletions

diff --git a/fs/xfs/libxfs/xfs_log_format.h b/fs/xfs/libxfs/xfs_log_format.h
index b351b9dc6561..2f41fa8477c9 100644
--- a/fs/xfs/libxfs/xfs_log_format.h
+++ b/fs/xfs/libxfs/xfs_log_format.h
@@ -613,7 +613,7 @@ typedef struct xfs_efi_log_format {
 	uint16_t		efi_size;	/* size of this item */
 	uint32_t		efi_nextents;	/* # extents to free */
 	uint64_t		efi_id;		/* efi identifier */
-	xfs_extent_t		efi_extents[1];	/* array of extents to free */
+	xfs_extent_t		efi_extents[];	/* array of extents to free */
 } xfs_efi_log_format_t;
 
 typedef struct xfs_efi_log_format_32 {
@@ -621,7 +621,7 @@ typedef struct xfs_efi_log_format_32 {
 	uint16_t		efi_size;	/* size of this item */
 	uint32_t		efi_nextents;	/* # extents to free */
 	uint64_t		efi_id;		/* efi identifier */
-	xfs_extent_32_t		efi_extents[1];	/* array of extents to free */
+	xfs_extent_32_t		efi_extents[];	/* array of extents to free */
 } __attribute__((packed)) xfs_efi_log_format_32_t;
 
 typedef struct xfs_efi_log_format_64 {
@@ -629,7 +629,7 @@ typedef struct xfs_efi_log_format_64 {
 	uint16_t		efi_size;	/* size of this item */
 	uint32_t		efi_nextents;	/* # extents to free */
 	uint64_t		efi_id;		/* efi identifier */
-	xfs_extent_64_t		efi_extents[1];	/* array of extents to free */
+	xfs_extent_64_t		efi_extents[];	/* array of extents to free */
 } xfs_efi_log_format_64_t;
 
 /*
@@ -642,7 +642,7 @@ typedef struct xfs_efd_log_format {
 	uint16_t		efd_size;	/* size of this item */
 	uint32_t		efd_nextents;	/* # of extents freed */
 	uint64_t		efd_efi_id;	/* id of corresponding efi */
-	xfs_extent_t		efd_extents[1];	/* array of extents freed */
+	xfs_extent_t		efd_extents[];	/* array of extents freed */
 } xfs_efd_log_format_t;
 
 typedef struct xfs_efd_log_format_32 {
@@ -650,7 +650,7 @@ typedef struct xfs_efd_log_format_32 {
 	uint16_t		efd_size;	/* size of this item */
 	uint32_t		efd_nextents;	/* # of extents freed */
 	uint64_t		efd_efi_id;	/* id of corresponding efi */
-	xfs_extent_32_t		efd_extents[1];	/* array of extents freed */
+	xfs_extent_32_t		efd_extents[];	/* array of extents freed */
 } __attribute__((packed)) xfs_efd_log_format_32_t;
 
 typedef struct xfs_efd_log_format_64 {
@@ -658,7 +658,7 @@ typedef struct xfs_efd_log_format_64 {
 	uint16_t		efd_size;	/* size of this item */
 	uint32_t		efd_nextents;	/* # of extents freed */
 	uint64_t		efd_efi_id;	/* id of corresponding efi */
-	xfs_extent_64_t		efd_extents[1];	/* array of extents freed */
+	xfs_extent_64_t		efd_extents[];	/* array of extents freed */
 } xfs_efd_log_format_64_t;
 
 /*
diff --git a/fs/xfs/xfs_extfree_item.c b/fs/xfs/xfs_extfree_item.c
index 27ccfcd82f04..466cc5c5cd33 100644
--- a/fs/xfs/xfs_extfree_item.c
+++ b/fs/xfs/xfs_extfree_item.c
@@ -76,7 +76,7 @@ xfs_efi_item_sizeof(
 	struct xfs_efi_log_item *efip)
 {
 	return sizeof(struct xfs_efi_log_format) +
-	       (efip->efi_format.efi_nextents - 1) * sizeof(xfs_extent_t);
+	       efip->efi_format.efi_nextents * sizeof(xfs_extent_t);
 }
 
 STATIC void
@@ -160,7 +160,7 @@ xfs_efi_init(
 	ASSERT(nextents > 0);
 	if (nextents > XFS_EFI_MAX_FAST_EXTENTS) {
 		size = (uint)(sizeof(struct xfs_efi_log_item) +
-			((nextents - 1) * sizeof(xfs_extent_t)));
+			(nextents * sizeof(xfs_extent_t)));
 		efip = kmem_zalloc(size, 0);
 	} else {
 		efip = kmem_cache_zalloc(xfs_efi_cache,
@@ -189,14 +189,19 @@ xfs_efi_copy_format(xfs_log_iovec_t *buf, xfs_efi_log_format_t *dst_efi_fmt)
 	xfs_efi_log_format_t *src_efi_fmt = buf->i_addr;
 	uint i;
 	uint len = sizeof(xfs_efi_log_format_t) +
-		(src_efi_fmt->efi_nextents - 1) * sizeof(xfs_extent_t);
+		src_efi_fmt->efi_nextents * sizeof(xfs_extent_t);
 	uint len32 = sizeof(xfs_efi_log_format_32_t) +
-		(src_efi_fmt->efi_nextents - 1) * sizeof(xfs_extent_32_t);
+		src_efi_fmt->efi_nextents * sizeof(xfs_extent_32_t);
 	uint len64 = sizeof(xfs_efi_log_format_64_t) +
-		(src_efi_fmt->efi_nextents - 1) * sizeof(xfs_extent_64_t);
+		src_efi_fmt->efi_nextents * sizeof(xfs_extent_64_t);
 
 	if (buf->i_len == len) {
-		memcpy((char *)dst_efi_fmt, (char*)src_efi_fmt, len);
+		memcpy(dst_efi_fmt, src_efi_fmt,
+		       offsetof(struct xfs_efi_log_format, efi_extents));
+		for (i = 0; i < src_efi_fmt->efi_nextents; i++)
+			memcpy(&dst_efi_fmt->efi_extents[i],
+			       &src_efi_fmt->efi_extents[i],
+			       sizeof(struct xfs_extent));
 		return 0;
 	} else if (buf->i_len == len32) {
 		xfs_efi_log_format_32_t *src_efi_fmt_32 = buf->i_addr;
@@ -256,7 +261,7 @@ xfs_efd_item_sizeof(
 	struct xfs_efd_log_item *efdp)
 {
 	return sizeof(xfs_efd_log_format_t) +
-	       (efdp->efd_format.efd_nextents - 1) * sizeof(xfs_extent_t);
+	       efdp->efd_format.efd_nextents * sizeof(xfs_extent_t);
 }
 
 STATIC void
@@ -341,7 +346,7 @@ xfs_trans_get_efd(
 
 	if (nextents > XFS_EFD_MAX_FAST_EXTENTS) {
 		efdp = kmem_zalloc(sizeof(struct xfs_efd_log_item) +
-				(nextents - 1) * sizeof(struct xfs_extent),
+				nextents * sizeof(struct xfs_extent),
 				0);
 	} else {
 		efdp = kmem_cache_zalloc(xfs_efd_cache,
@@ -733,6 +738,12 @@ xlog_recover_efi_commit_pass2(
 
 	efi_formatp = item->ri_buf[0].i_addr;
 
+	if (item->ri_buf[0].i_len <
+			offsetof(struct xfs_efi_log_format, efi_extents)) {
+		XFS_ERROR_REPORT(__func__, XFS_ERRLEVEL_LOW, log->l_mp);
+		return -EFSCORRUPTED;
+	}
+
 	efip = xfs_efi_init(mp, efi_formatp->efi_nextents);
 	error = xfs_efi_copy_format(&item->ri_buf[0], &efip->efi_format);
 	if (error) {
@@ -772,9 +783,9 @@ xlog_recover_efd_commit_pass2(
 
 	efd_formatp = item->ri_buf[0].i_addr;
 	ASSERT((item->ri_buf[0].i_len == (sizeof(xfs_efd_log_format_32_t) +
-		((efd_formatp->efd_nextents - 1) * sizeof(xfs_extent_32_t)))) ||
+		(efd_formatp->efd_nextents * sizeof(xfs_extent_32_t)))) ||
 	       (item->ri_buf[0].i_len == (sizeof(xfs_efd_log_format_64_t) +
-		((efd_formatp->efd_nextents - 1) * sizeof(xfs_extent_64_t)))));
+		(efd_formatp->efd_nextents * sizeof(xfs_extent_64_t)))));
 
 	xlog_recover_release_intent(log, XFS_LI_EFI, efd_formatp->efd_efi_id);
 	return 0;
diff --git a/fs/xfs/xfs_ondisk.h b/fs/xfs/xfs_ondisk.h
index 19c1df00b48e..9737b5a9f405 100644
--- a/fs/xfs/xfs_ondisk.h
+++ b/fs/xfs/xfs_ondisk.h
@@ -118,10 +118,10 @@ xfs_check_ondisk_structs(void)
 	/* log structures */
 	XFS_CHECK_STRUCT_SIZE(struct xfs_buf_log_format,	88);
 	XFS_CHECK_STRUCT_SIZE(struct xfs_dq_logformat,		24);
-	XFS_CHECK_STRUCT_SIZE(struct xfs_efd_log_format_32,	28);
-	XFS_CHECK_STRUCT_SIZE(struct xfs_efd_log_format_64,	32);
-	XFS_CHECK_STRUCT_SIZE(struct xfs_efi_log_format_32,	28);
-	XFS_CHECK_STRUCT_SIZE(struct xfs_efi_log_format_64,	32);
+	XFS_CHECK_STRUCT_SIZE(struct xfs_efd_log_format_32,	16);
+	XFS_CHECK_STRUCT_SIZE(struct xfs_efd_log_format_64,	16);
+	XFS_CHECK_STRUCT_SIZE(struct xfs_efi_log_format_32,	16);
+	XFS_CHECK_STRUCT_SIZE(struct xfs_efi_log_format_64,	16);
 	XFS_CHECK_STRUCT_SIZE(struct xfs_extent_32,		12);
 	XFS_CHECK_STRUCT_SIZE(struct xfs_extent_64,		16);
 	XFS_CHECK_STRUCT_SIZE(struct xfs_log_dinode,		176);
@@ -146,6 +146,9 @@ xfs_check_ondisk_structs(void)
 	XFS_CHECK_OFFSET(struct xfs_bui_log_format, bui_extents,	16);
 	XFS_CHECK_OFFSET(struct xfs_cui_log_format, cui_extents,	16);
 	XFS_CHECK_OFFSET(struct xfs_rui_log_format, rui_extents,	16);
+	XFS_CHECK_OFFSET(struct xfs_efi_log_format, efi_extents,	16);
+	XFS_CHECK_OFFSET(struct xfs_efi_log_format_32, efi_extents,	16);
+	XFS_CHECK_OFFSET(struct xfs_efi_log_format_64, efi_extents,	16);
 
 	/*
 	 * The v5 superblock format extended several v4 header structures with
diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
index f029c6702dda..8485e3b37ca0 100644
--- a/fs/xfs/xfs_super.c
+++ b/fs/xfs/xfs_super.c
@@ -2029,7 +2029,7 @@ xfs_init_caches(void)
 
 	xfs_efd_cache = kmem_cache_create("xfs_efd_item",
 					(sizeof(struct xfs_efd_log_item) +
-					(XFS_EFD_MAX_FAST_EXTENTS - 1) *
+					XFS_EFD_MAX_FAST_EXTENTS *
 					sizeof(struct xfs_extent)),
 					0, 0, NULL);
 	if (!xfs_efd_cache)
@@ -2037,7 +2037,7 @@ xfs_init_caches(void)
 
 	xfs_efi_cache = kmem_cache_create("xfs_efi_item",
 					 (sizeof(struct xfs_efi_log_item) +
-					 (XFS_EFI_MAX_FAST_EXTENTS - 1) *
+					 XFS_EFI_MAX_FAST_EXTENTS *
 					 sizeof(struct xfs_extent)),
 					 0, 0, NULL);
 	if (!xfs_efi_cache)