linux-kernel - [PATCH v2 07/13] recordmcount: Remove redundant cleanup() calls

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <1a1bc8fc3b04c4d42aff0de5b7e78ebb8a9c4919.1560285597.git.mhelsley@vmware.com>
Date:   Tue, 11 Jun 2019 15:21:49 -0700
From:   Matt Helsley <mhelsley@...are.com>
To:     LKML <linux-kernel@...r.kernel.org>
CC:     Ingo Molnar <mingo@...nel.org>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Matt Helsley <mhelsley@...are.com>
Subject: [PATCH v2 07/13] recordmcount: Remove redundant cleanup() calls

Redundant cleanup calls were introduced when transitioning from
the old error/success handling via setjmp/longjmp -- the longjmp
ensured the cleanup() call only happened once but replacing
the success_file()/fail_file() calls with cleanup() meant that
multiple cleanup() calls can happen as we return from function
calls.

In do_file(), looking just before and after the "goto out" jumps we
can see that multiple cleanups() are being performed. We remove
cleanup() calls from the nested functions because it makes the code
easier to review -- the resources being cleaned up are generally
allocated and initialized in the callers so freeing them there
makes more sense.

Other redundant cleanup() calls:

mmap_file() is only called from do_file() and, if mmap_file() fails,
then we goto out and do cleanup() there too.

write_file() is only called from do_file() and do_file()
calls cleanup() unconditionally after returning from write_file()
therefore the cleanup() calls in write_file() are not necessary.

find_secsym_ndx(), called from do_func()'s for-loop, when we are
cleaning up here it's obvious that we break out of the loop and
do another cleanup().

__has_rel_mcount() is called from two parts of do_func()
and calls cleanup(). In theory we move them into do_func(), however
these in turn prove redundant so another simplification step
removes them as well.

Signed-off-by: Matt Helsley <mhelsley@...are.com>
---
 scripts/recordmcount.c | 13 -------------
 scripts/recordmcount.h |  2 --
 2 files changed, 15 deletions(-)

diff --git a/scripts/recordmcount.c b/scripts/recordmcount.c
index 9ae975ccf2dc..111419c282d3 100644
--- a/scripts/recordmcount.c
+++ b/scripts/recordmcount.c
@@ -258,17 +258,14 @@ static void *mmap_file(char const *fname)
 	fd_map = open(fname, O_RDONLY);
 	if (fd_map < 0) {
 		perror(fname);
-		cleanup();
 		return NULL;
 	}
 	if (fstat(fd_map, &sb) < 0) {
 		perror(fname);
-		cleanup();
 		goto out;
 	}
 	if (!S_ISREG(sb.st_mode)) {
 		fprintf(stderr, "not a regular file: %s\n", fname);
-		cleanup();
 		goto out;
 	}
 	file_map = mmap(0, sb.st_size, PROT_READ|PROT_WRITE, MAP_PRIVATE,
@@ -314,13 +311,11 @@ static int write_file(const char *fname)
 	fd_map = open(tmp_file, O_WRONLY | O_TRUNC | O_CREAT, sb.st_mode);
 	if (fd_map < 0) {
 		perror(fname);
-		cleanup();
 		return -1;
 	}
 	n = write(fd_map, file_map, sb.st_size);
 	if (n != sb.st_size) {
 		perror("write");
-		cleanup();
 		close(fd_map);
 		return -1;
 	}
@@ -328,7 +323,6 @@ static int write_file(const char *fname)
 		n = write(fd_map, file_append, file_append_size);
 		if (n != file_append_size) {
 			perror("write");
-			cleanup();
 			close(fd_map);
 			return -1;
 		}
@@ -336,7 +330,6 @@ static int write_file(const char *fname)
 	close(fd_map);
 	if (rename(tmp_file, fname) < 0) {
 		perror(fname);
-		cleanup();
 		return -1;
 	}
 	return 0;
@@ -458,7 +451,6 @@ static int do_file(char const *const fname)
 	default:
 		fprintf(stderr, "unrecognized ELF data encoding %d: %s\n",
 			ehdr->e_ident[EI_DATA], fname);
-		cleanup();
 		goto out;
 	case ELFDATA2LSB:
 		if (*(unsigned char const *)&endian != 1) {
@@ -491,7 +483,6 @@ static int do_file(char const *const fname)
 	    w2(ehdr->e_type) != ET_REL ||
 	    ehdr->e_ident[EI_VERSION] != EV_CURRENT) {
 		fprintf(stderr, "unrecognized ET_REL file %s\n", fname);
-		cleanup();
 		goto out;
 	}
 
@@ -500,7 +491,6 @@ static int do_file(char const *const fname)
 	default:
 		fprintf(stderr, "unrecognized e_machine %u %s\n",
 			w2(ehdr->e_machine), fname);
-		cleanup();
 		goto out;
 	case EM_386:
 		reltype = R_386_32;
@@ -544,14 +534,12 @@ static int do_file(char const *const fname)
 	default:
 		fprintf(stderr, "unrecognized ELF class %d %s\n",
 			ehdr->e_ident[EI_CLASS], fname);
-		cleanup();
 		goto out;
 	case ELFCLASS32:
 		if (w2(ehdr->e_ehsize) != sizeof(Elf32_Ehdr)
 		||  w2(ehdr->e_shentsize) != sizeof(Elf32_Shdr)) {
 			fprintf(stderr,
 				"unrecognized ET_REL file: %s\n", fname);
-			cleanup();
 			goto out;
 		}
 		if (w2(ehdr->e_machine) == EM_MIPS) {
@@ -567,7 +555,6 @@ static int do_file(char const *const fname)
 		||  w2(ghdr->e_shentsize) != sizeof(Elf64_Shdr)) {
 			fprintf(stderr,
 				"unrecognized ET_REL file: %s\n", fname);
-			cleanup();
 			goto out;
 		}
 		if (w2(ghdr->e_machine) == EM_S390) {
diff --git a/scripts/recordmcount.h b/scripts/recordmcount.h
index 3198459f7431..b7348f1af758 100644
--- a/scripts/recordmcount.h
+++ b/scripts/recordmcount.h
@@ -468,7 +468,6 @@ static unsigned find_secsym_ndx(unsigned const txtndx,
 	}
 	fprintf(stderr, "Cannot find symbol for section %u: %s.\n",
 		txtndx, txtname);
-	cleanup();
 	return missing_sym;
 }
 
@@ -487,7 +486,6 @@ static char const * __has_rel_mcount(Elf_Shdr const *const relhdr, /* reltype */
 	if (strcmp("__mcount_loc", txtname) == 0) {
 		fprintf(stderr, "warning: __mcount_loc already exists: %s\n",
 			fname);
-		cleanup();
 		return already_has_rel_mcount;
 	}
 	if (w(txthdr->sh_type) != SHT_PROGBITS ||
-- 
2.20.1