From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([140.186.70.92]:46676) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1QRkix-0004wV-Bz for qemu-devel@nongnu.org; Wed, 01 Jun 2011 08:40:36 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1QRkiv-0005g3-Lp for qemu-devel@nongnu.org; Wed, 01 Jun 2011 08:40:35 -0400 Received: from eu1sys200aog119.obsmtp.com ([207.126.144.147]:39409) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1QRkiu-0005fg-T8 for qemu-devel@nongnu.org; Wed, 01 Jun 2011 08:40:33 -0400 From: =?UTF-8?q?C=C3=A9dric=20VINCENT?= Date: Wed, 1 Jun 2011 14:36:38 +0200 Message-ID: <1306931798-2475-1-git-send-email-cedric.vincent@st.com> MIME-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8bit Subject: [Qemu-devel] [PATCH] linux-user: Fix the load of ELF files that have no "useful" symbol List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: =?UTF-8?q?C=C3=A9dric=20VINCENT?= , Riku Voipio , Yves JANIN This patch fixes a "double free()" due to "realloc(syms, 0)" in the loader when the ELF file has no "useful" symbol, as with the following example (compiled with "sh4-linux-gcc -nostdlib"): .text .align 1 .global _start _start: mov #1, r3 trapa #40 // syscall(__NR_exit) nop The bug appears when the log (option "-d") is enabled. Signed-off-by: Cédric VINCENT Signed-off-by: Yves JANIN --- linux-user/elfload.c | 34 +++++++++++++++++++--------------- 1 files changed, 19 insertions(+), 15 deletions(-) diff --git a/linux-user/elfload.c b/linux-user/elfload.c index 6f67286..4e77c89 100644 --- a/linux-user/elfload.c +++ b/linux-user/elfload.c @@ -1650,9 +1650,9 @@ static void load_symbols(struct elfhdr *hdr, int fd, abi_ulong load_bias) { int i, shnum, nsyms, sym_idx = 0, str_idx = 0; struct elf_shdr *shdr; - char *strings; - struct syminfo *s; - struct elf_sym *syms, *new_syms; + char *strings = NULL; + struct syminfo *s = NULL; + struct elf_sym *new_syms, *syms = NULL; shnum = hdr->e_shnum; i = shnum * sizeof(struct elf_shdr); @@ -1677,24 +1677,19 @@ static void load_symbols(struct elfhdr *hdr, int fd, abi_ulong load_bias) /* Now know where the strtab and symtab are. Snarf them. */ s = malloc(sizeof(*s)); if (!s) { - return; + goto give_up; } i = shdr[str_idx].sh_size; s->disas_strtab = strings = malloc(i); if (!strings || pread(fd, strings, i, shdr[str_idx].sh_offset) != i) { - free(s); - free(strings); - return; + goto give_up; } i = shdr[sym_idx].sh_size; syms = malloc(i); if (!syms || pread(fd, syms, i, shdr[sym_idx].sh_offset) != i) { - free(s); - free(strings); - free(syms); - return; + goto give_up; } nsyms = i / sizeof(struct elf_sym); @@ -1717,16 +1712,18 @@ static void load_symbols(struct elfhdr *hdr, int fd, abi_ulong load_bias) } } + /* No "useful" symbol. */ + if (nsyms == 0) { + goto give_up; + } + /* Attempt to free the storage associated with the local symbols that we threw away. Whether or not this has any effect on the memory allocation depends on the malloc implementation and how many symbols we managed to discard. */ new_syms = realloc(syms, nsyms * sizeof(*syms)); if (new_syms == NULL) { - free(s); - free(syms); - free(strings); - return; + goto give_up; } syms = new_syms; @@ -1741,6 +1738,13 @@ static void load_symbols(struct elfhdr *hdr, int fd, abi_ulong load_bias) s->lookup_symbol = lookup_symbolxx; s->next = syminfos; syminfos = s; + + return; + +give_up: + free(s); + free(strings); + free(syms); } int load_elf_binary(struct linux_binprm * bprm, struct target_pt_regs * regs, -- 1.7.5.1