From 1e06262da615fcc0ddd658f96c5673a73b856fb6 Mon Sep 17 00:00:00 2001 From: Peter Maydell Date: Sat, 4 Feb 2017 23:05:33 +0000 Subject: linux-user: Use correct types in load_symbols() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Coverity doesn't like the code in load_symbols() which assumes it can use 'int' for a variable that might hold an offset into the guest ELF file, because in a 64-bit guest that could overflow. Guest binaries with 2GB sections aren't very likely and this isn't a security issue because we fully trust the guest linux-user binary anyway, but we might as well use the right types, which will placate Coverity. Use uint64_t to hold section sizes, and bail out if the symbol table is too large rather than just overflowing an int. (Coverity issue CID1005776) Signed-off-by: Peter Maydell Reviewed-by: Laurent Vivier Reviewed-by: Philippe Mathieu-Daudé Message-Id: <1486249533-5260-1-git-send-email-peter.maydell@linaro.org> Signed-off-by: Laurent Vivier --- linux-user/elfload.c | 22 +++++++++++++++------- 1 file changed, 15 insertions(+), 7 deletions(-) (limited to 'linux-user') diff --git a/linux-user/elfload.c b/linux-user/elfload.c index 8271227..f520d77 100644 --- a/linux-user/elfload.c +++ b/linux-user/elfload.c @@ -2262,6 +2262,7 @@ static int symcmp(const void *s0, const void *s1) static void load_symbols(struct elfhdr *hdr, int fd, abi_ulong load_bias) { int i, shnum, nsyms, sym_idx = 0, str_idx = 0; + uint64_t segsz; struct elf_shdr *shdr; char *strings = NULL; struct syminfo *s = NULL; @@ -2293,19 +2294,26 @@ static void load_symbols(struct elfhdr *hdr, int fd, abi_ulong load_bias) goto give_up; } - i = shdr[str_idx].sh_size; - s->disas_strtab = strings = g_try_malloc(i); - if (!strings || pread(fd, strings, i, shdr[str_idx].sh_offset) != i) { + segsz = shdr[str_idx].sh_size; + s->disas_strtab = strings = g_try_malloc(segsz); + if (!strings || + pread(fd, strings, segsz, shdr[str_idx].sh_offset) != segsz) { goto give_up; } - i = shdr[sym_idx].sh_size; - syms = g_try_malloc(i); - if (!syms || pread(fd, syms, i, shdr[sym_idx].sh_offset) != i) { + segsz = shdr[sym_idx].sh_size; + syms = g_try_malloc(segsz); + if (!syms || pread(fd, syms, segsz, shdr[sym_idx].sh_offset) != segsz) { goto give_up; } - nsyms = i / sizeof(struct elf_sym); + if (segsz / sizeof(struct elf_sym) > INT_MAX) { + /* Implausibly large symbol table: give up rather than ploughing + * on with the number of symbols calculation overflowing + */ + goto give_up; + } + nsyms = segsz / sizeof(struct elf_sym); for (i = 0; i < nsyms; ) { bswap_sym(syms + i); /* Throw away entries which we do not need. */ -- cgit v1.1