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commit a291ab2d40e97a5ae0c07bf62f04ad7c438f66d0
parent 62d2e531d7f353a77356c461bac12a0dc23aff7c
Author: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Date:   Fri, 12 Oct 2018 12:54:26 +0200

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

Diffstat:
Mlib/Makefile | 1-
Mlib/bch.c | 17+++++++++++++----
2 files changed, 13 insertions(+), 5 deletions(-)

diff --git a/lib/Makefile b/lib/Makefile @@ -119,7 +119,6 @@ obj-$(CONFIG_ZLIB_INFLATE) += zlib_inflate/ obj-$(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 @@ -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 @@ void encode_bch(struct bch_control *bch, const uint8_t *data, 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 @@ struct bch_control *init_bch(int m, int t, unsigned int prim_poly) */ 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 */