[ELF] - Recommit "[ELF] - Do not forget to fill last bytes of PT_LOADs with trap instructions."

George Rimar · George Rimar · commit f7ef2a13f674 · 2017-08-21T08:31:14.000Z
With fix: explicitly specify ouput format for hexdump tool call. Original commit message: [ELF] - Do not forget to fill last bytes of PT_LOADs with trap instructions. Previously last 4 bytes of executable loads were not filled with trap instructions, patch fixes this bug. Differential revision: https://reviews.llvm.org/D36262 llvm-svn: 311315
diff --git a/lld/ELF/Writer.cpp b/lld/ELF/Writer.cpp
@@ -1856,7 +1856,7 @@ template <class ELFT> void Writer<ELFT>::writeSectionsBinary() {
 }
 
 static void fillTrap(uint8_t *I, uint8_t *End) {
-  for (; I + 4 < End; I += 4)
+  for (; I + 4 <= End; I += 4)
     memcpy(I, &Target->TrapInstr, 4);
 }
 
diff --git a/lld/test/ELF/build-id.s b/lld/test/ELF/build-id.s
@@ -48,15 +48,15 @@ _start:
 # DEFAULT:      Contents of section .note.test:
 # DEFAULT:      Contents of section .note.gnu.build-id:
 # DEFAULT-NEXT: 04000000 08000000 03000000 474e5500  ............GNU.
-# DEFAULT-NEXT: d618a375 bc6301ec
+# DEFAULT-NEXT: b0148597 ba5eb7e9
 
 # MD5:      Contents of section .note.gnu.build-id:
 # MD5-NEXT: 04000000 10000000 03000000 474e5500  ............GNU.
-# MD5-NEXT: 051084fe ce1f30ed e035b79e 11262808
+# MD5-NEXT: dce3bcaf 5219454c e89a1fc7 86ab17bd
 
 # SHA1:      Contents of section .note.gnu.build-id:
 # SHA1-NEXT: 04000000 14000000 03000000 474e5500  ............GNU.
-# SHA1-NEXT: c70b9aec 903fd291 8b677cd8 1e04f8b6
+# SHA1-NEXT: 2f716666 fe3668fe 370a02a1 579c3eb2
 
 # UUID:      Contents of section .note.gnu.build-id:
 # UUID-NEXT: 04000000 10000000 03000000 474e5500  ............GNU.
diff --git a/lld/test/ELF/fill-trap.s b/lld/test/ELF/fill-trap.s
@@ -0,0 +1,25 @@
+# REQUIRES: x86
+
+# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t
+# RUN: ld.lld %t -o %t2
+# RUN: llvm-readobj -program-headers %t2 | FileCheck %s
+# RUN: hexdump -v -s 0x0001ff0 -x %t2 | FileCheck %s -check-prefix=FILL
+
+# CHECK: ProgramHeader {
+# CHECK:   Type: PT_LOAD
+# CHECK:   Offset: 0x1000
+# CHECK-NEXT:   VirtualAddress:
+# CHECK-NEXT:   PhysicalAddress:
+# CHECK-NEXT:   FileSize: 4096
+# CHECK-NEXT:   MemSize:
+# CHECK-NEXT:   Flags [
+# CHECK-NEXT:     PF_R
+# CHECK-NEXT:     PF_X
+# CHECK-NEXT:   ]
+
+## Check that executable page is filled with traps at it's end.
+# FILL: 0001ff0 cccc cccc cccc cccc cccc cccc cccc cccc
+
+.globl _start
+_start:
+  nop

Original file line number	Diff line number	Diff line change
`@@ -1856,7 +1856,7 @@ template <class ELFT> void Writer<ELFT>::writeSectionsBinary() {`
`1856`	`1856`	`}`
`1857`	`1857`
`1858`	`1858`	`static void fillTrap(uint8_t I, uint8_t End) {`
`1859`		`- for (; I + 4 < End; I += 4)`
	`1859`	`+ for (; I + 4 <= End; I += 4)`
`1860`	`1860`	`memcpy(I, &Target->TrapInstr, 4);`
`1861`	`1861`	`}`
`1862`	`1862`