From 58bea4144d235cee5bb51203b032ddafd6d1cf8d Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Wed, 19 Oct 2016 00:08:04 +0200 Subject: [PATCH] latent_entropy: Fix wrong gcc code generation with 64 bit variables The stack frame size could grow too large when the plugin used long long on 32-bit architectures when the given function had too many basic blocks. The gcc warning was: drivers/pci/hotplug/ibmphp_ebda.c: In function 'ibmphp_access_ebda': drivers/pci/hotplug/ibmphp_ebda.c:409:1: warning: the frame size of 1108 bytes is larger than 1024 bytes [-Wframe-larger-than=] This switches latent_entropy from u64 to unsigned long. Thanks to PaX Team and Emese Revfy for the patch. Signed-off-by: Kees Cook --- mm/page_alloc.c | 2 +- scripts/gcc-plugins/latent_entropy_plugin.c | 19 +++++++++---------- 2 files changed, 10 insertions(+), 11 deletions(-) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 2b3bf6767d54..1b10c14de5db 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -92,7 +92,7 @@ int _node_numa_mem_[MAX_NUMNODES]; #endif #ifdef CONFIG_GCC_PLUGIN_LATENT_ENTROPY -volatile u64 latent_entropy __latent_entropy; +volatile unsigned long latent_entropy __latent_entropy; EXPORT_SYMBOL(latent_entropy); #endif diff --git a/scripts/gcc-plugins/latent_entropy_plugin.c b/scripts/gcc-plugins/latent_entropy_plugin.c index 9d3d4adf3be8..8160f1c1b56e 100644 --- a/scripts/gcc-plugins/latent_entropy_plugin.c +++ b/scripts/gcc-plugins/latent_entropy_plugin.c @@ -340,7 +340,7 @@ static enum tree_code get_op(tree *rhs) break; } if (rhs) - *rhs = build_int_cstu(unsigned_intDI_type_node, random_const); + *rhs = build_int_cstu(long_unsigned_type_node, random_const); return op; } @@ -372,7 +372,7 @@ static void __perturb_latent_entropy(gimple_stmt_iterator *gsi, enum tree_code op; /* 1. create temporary copy of latent_entropy */ - temp = create_var(unsigned_intDI_type_node, "tmp_latent_entropy"); + temp = create_var(long_unsigned_type_node, "temp_latent_entropy"); /* 2. read... */ add_referenced_var(latent_entropy_decl); @@ -459,13 +459,13 @@ static void init_local_entropy(basic_block bb, tree local_entropy) gsi_insert_before(&gsi, call, GSI_NEW_STMT); update_stmt(call); - udi_frame_addr = fold_convert(unsigned_intDI_type_node, frame_addr); + udi_frame_addr = fold_convert(long_unsigned_type_node, frame_addr); assign = gimple_build_assign(local_entropy, udi_frame_addr); gsi_insert_after(&gsi, assign, GSI_NEW_STMT); update_stmt(assign); /* 3. create temporary copy of latent_entropy */ - tmp = create_var(unsigned_intDI_type_node, "tmp_latent_entropy"); + tmp = create_var(long_unsigned_type_node, "temp_latent_entropy"); /* 4. read the global entropy variable into local entropy */ add_referenced_var(latent_entropy_decl); @@ -480,7 +480,7 @@ static void init_local_entropy(basic_block bb, tree local_entropy) update_stmt(assign); rand_cst = get_random_const(); - rand_const = build_int_cstu(unsigned_intDI_type_node, rand_cst); + rand_const = build_int_cstu(long_unsigned_type_node, rand_cst); op = get_op(NULL); assign = create_assign(op, local_entropy, local_entropy, rand_const); gsi_insert_after(&gsi, assign, GSI_NEW_STMT); @@ -529,7 +529,7 @@ static unsigned int latent_entropy_execute(void) } /* 1. create the local entropy variable */ - local_entropy = create_var(unsigned_intDI_type_node, "local_entropy"); + local_entropy = create_var(long_unsigned_type_node, "local_entropy"); /* 2. initialize the local entropy variable */ init_local_entropy(bb, local_entropy); @@ -561,10 +561,9 @@ static void latent_entropy_start_unit(void *gcc_data __unused, if (in_lto_p) return; - /* extern volatile u64 latent_entropy */ - gcc_assert(TYPE_PRECISION(long_long_unsigned_type_node) == 64); - quals = TYPE_QUALS(long_long_unsigned_type_node) | TYPE_QUAL_VOLATILE; - type = build_qualified_type(long_long_unsigned_type_node, quals); + /* extern volatile unsigned long latent_entropy */ + quals = TYPE_QUALS(long_unsigned_type_node) | TYPE_QUAL_VOLATILE; + type = build_qualified_type(long_unsigned_type_node, quals); id = get_identifier("latent_entropy"); latent_entropy_decl = build_decl(UNKNOWN_LOCATION, VAR_DECL, id, type); -- 2.20.1