mirrors/qemu
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

linux-user: Use correct types in load_symbols()

Browse Source 
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 <peter.maydell@linaro.org>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-Id: <1486249533-5260-1-git-send-email-peter.maydell@linaro.org>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
This commit is contained in:
Peter Maydell 2017-02-04 23:05:33 +00:00 committed by Laurent Vivier
parent 26920a2961
commit 1e06262da6
1 changed files with 15 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

22
linux-user/elfload.c
View File

@ -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. */