From 3c076c9642fd8877def0a0597ec7e4adfb5aa3b3 Mon Sep 17 00:00:00 2001 From: Jakub Jelinek Date: Tue, 28 Jan 2020 08:44:07 +0100 Subject: [PATCH] gimple-fold: Fix buffer overflow in fold_array_ctor_reference [PR93454] libgcrypt FAILs to build on aarch64-linux with *** stack smashing detected ***: terminated when gcc is compiled with -D_FORTIFY_SOURCE=2. The problem is if fold_array_ctor_reference is called with size equal to or very close to MAX_BITSIZE_MODE_ANY_MODE bits and non-zero inner_offset. The first native_encode_expr is called with that inner_offset and bufoff 0, the subsequent ones with offset of 0, and bufoff elt_size - inner_offset, 2 * elt_size - inner_offset etc. So, e.g. on the testcase where we start with inner_offset 1 and size is e.g. 256 bytes and elt_size 4 bytes we then call native_encode_expr at bufoff 251 and then 255, but that one overwrites 3 bytes beyond the buf array. The following patch fixes that. In addition, it avoids calling elt_size.to_uhwi () all the time, and punts if elt_sz would be too large. 2020-01-28 Jakub Jelinek PR tree-optimization/93454 * gimple-fold.c (fold_array_ctor_reference): Perform elt_size.to_uhwi () just once, instead of calling it in every iteration. Punt if that value is above size of the temporary buffer. Decrease third native_encode_expr argument when bufoff + elt_sz is above size of buf. * gcc.dg/pr93454.c: New test. --- gcc/ChangeLog | 9 +++++++++ gcc/gimple-fold.c | 13 ++++++++----- gcc/testsuite/ChangeLog | 5 +++++ gcc/testsuite/gcc.dg/pr93454.c | 25 +++++++++++++++++++++++++ 4 files changed, 47 insertions(+), 5 deletions(-) create mode 100644 gcc/testsuite/gcc.dg/pr93454.c diff --git a/gcc/ChangeLog b/gcc/ChangeLog index af0945f..6db98ed 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,12 @@ +2020-01-28 Jakub Jelinek + + PR tree-optimization/93454 + * gimple-fold.c (fold_array_ctor_reference): Perform + elt_size.to_uhwi () just once, instead of calling it in every + iteration. Punt if that value is above size of the temporary + buffer. Decrease third native_encode_expr argument when + bufoff + elt_sz is above size of buf. + 2020-01-27 Joseph Myers * config/mips/mips.c (mips_declare_object_name) diff --git a/gcc/gimple-fold.c b/gcc/gimple-fold.c index 569f91e..ed22592 100644 --- a/gcc/gimple-fold.c +++ b/gcc/gimple-fold.c @@ -6665,12 +6665,14 @@ fold_array_ctor_reference (tree type, tree ctor, /* And offset within the access. */ inner_offset = offset % (elt_size.to_uhwi () * BITS_PER_UNIT); - if (size > elt_size.to_uhwi () * BITS_PER_UNIT) + unsigned HOST_WIDE_INT elt_sz = elt_size.to_uhwi (); + if (size > elt_sz * BITS_PER_UNIT) { /* native_encode_expr constraints. */ if (size > MAX_BITSIZE_MODE_ANY_MODE || size % BITS_PER_UNIT != 0 - || inner_offset % BITS_PER_UNIT != 0) + || inner_offset % BITS_PER_UNIT != 0 + || elt_sz > MAX_BITSIZE_MODE_ANY_MODE / BITS_PER_UNIT) return NULL_TREE; unsigned ctor_idx; @@ -6701,10 +6703,11 @@ fold_array_ctor_reference (tree type, tree ctor, index = wi::umax (index, access_index); do { - int len = native_encode_expr (val, buf + bufoff, - elt_size.to_uhwi (), + if (bufoff + elt_sz > sizeof (buf)) + elt_sz = sizeof (buf) - bufoff; + int len = native_encode_expr (val, buf + bufoff, elt_sz, inner_offset / BITS_PER_UNIT); - if (len != elt_size - inner_offset / BITS_PER_UNIT) + if (len != (int) elt_sz - inner_offset / BITS_PER_UNIT) return NULL_TREE; inner_offset = 0; bufoff += len; diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog index f83f18b..44d8e67 100644 --- a/gcc/testsuite/ChangeLog +++ b/gcc/testsuite/ChangeLog @@ -1,3 +1,8 @@ +2020-01-28 Jakub Jelinek + + PR tree-optimization/93454 + * gcc.dg/pr93454.c: New test. + 2020-01-27 David Malcolm PR analyzer/93451 diff --git a/gcc/testsuite/gcc.dg/pr93454.c b/gcc/testsuite/gcc.dg/pr93454.c new file mode 100644 index 0000000..84c47cf --- /dev/null +++ b/gcc/testsuite/gcc.dg/pr93454.c @@ -0,0 +1,25 @@ +/* PR tree-optimization/93454 */ +/* { dg-do compile } */ +/* { dg-options "-O2 -g" } */ + +#if __SIZEOF_INT__ == 4 && __CHAR_BIT__ == 8 +#define A(n) n, n + 0x01010101, n + 0x02020202, n + 0x03030303 +#define B(n) A (n), A (n + 0x04040404), A (n + 0x08080808), A (n + 0x0c0c0c0c) +#define C(n) B (n), B (n + 0x10101010), B (n + 0x20202020), B (n + 0x30303030) +#define D(n) C (n), C (n + 0x40404040), C (n + 0x80808080U), C (n + 0xc0c0c0c0U) +const unsigned int a[64] = { C (0) }; +const unsigned int b[256] = { D (0) }; +const unsigned int c[32] = { B (0), B (0x10101010) }; +const unsigned int d[16] = { B (0) }; +const unsigned int e[8] = { A (0), A (0x04040404) }; + +void +foo (void) +{ + const unsigned char *s = ((const unsigned char *) a) + 1; + const unsigned char *t = ((const unsigned char *) b) + 1; + const unsigned char *u = ((const unsigned char *) c) + 1; + const unsigned char *v = ((const unsigned char *) d) + 1; + const unsigned char *w = ((const unsigned char *) e) + 1; +} +#endif -- 2.7.4