Merge tag 'mtd/fixes-for-4.19-rc8' of git://git.infradead.org/linux-mtd
Boris writes:
"mdt: fix for 4.19-rc8
* Fix a stack overflow in lib/bch.c"
* tag 'mtd/fixes-for-4.19-rc8' of git://git.infradead.org/linux-mtd:
lib/bch: fix possible stack overrun
diff --git a/lib/Makefile b/lib/Makefile
index ca3f7eb..4238764 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -119,7 +119,6 @@
obj-$(CONFIG_ZLIB_DEFLATE) += zlib_deflate/
obj-$(CONFIG_REED_SOLOMON) += reed_solomon/
obj-$(CONFIG_BCH) += bch.o
-CFLAGS_bch.o := $(call cc-option,-Wframe-larger-than=4500)
obj-$(CONFIG_LZO_COMPRESS) += lzo/
obj-$(CONFIG_LZO_DECOMPRESS) += lzo/
obj-$(CONFIG_LZ4_COMPRESS) += lz4/
diff --git a/lib/bch.c b/lib/bch.c
index 7b0f200..5db6d3a 100644
--- a/lib/bch.c
+++ b/lib/bch.c
@@ -79,20 +79,19 @@
#define GF_T(_p) (CONFIG_BCH_CONST_T)
#define GF_N(_p) ((1 << (CONFIG_BCH_CONST_M))-1)
#define BCH_MAX_M (CONFIG_BCH_CONST_M)
+#define BCH_MAX_T (CONFIG_BCH_CONST_T)
#else
#define GF_M(_p) ((_p)->m)
#define GF_T(_p) ((_p)->t)
#define GF_N(_p) ((_p)->n)
-#define BCH_MAX_M 15
+#define BCH_MAX_M 15 /* 2KB */
+#define BCH_MAX_T 64 /* 64 bit correction */
#endif
-#define BCH_MAX_T (((1 << BCH_MAX_M) - 1) / BCH_MAX_M)
-
#define BCH_ECC_WORDS(_p) DIV_ROUND_UP(GF_M(_p)*GF_T(_p), 32)
#define BCH_ECC_BYTES(_p) DIV_ROUND_UP(GF_M(_p)*GF_T(_p), 8)
#define BCH_ECC_MAX_WORDS DIV_ROUND_UP(BCH_MAX_M * BCH_MAX_T, 32)
-#define BCH_ECC_MAX_BYTES DIV_ROUND_UP(BCH_MAX_M * BCH_MAX_T, 8)
#ifndef dbg
#define dbg(_fmt, args...) do {} while (0)
@@ -202,6 +201,9 @@
const uint32_t * const tab3 = tab2 + 256*(l+1);
const uint32_t *pdata, *p0, *p1, *p2, *p3;
+ if (WARN_ON(r_bytes > sizeof(r)))
+ return;
+
if (ecc) {
/* load ecc parity bytes into internal 32-bit buffer */
load_ecc8(bch, bch->ecc_buf, ecc);
@@ -1285,6 +1287,13 @@
*/
goto fail;
+ if (t > BCH_MAX_T)
+ /*
+ * we can support larger than 64 bits if necessary, at the
+ * cost of higher stack usage.
+ */
+ goto fail;
+
/* sanity checks */
if ((t < 1) || (m*t >= ((1 << m)-1)))
/* invalid t value */
