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improve error handling in map_library and support long phdrs

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previously, errno could be meaningless when the caller wrote it to the
dlerror string or stderr. try to make it meaningful. also, fix
incorrect check for over-long program headers and instead actually
support them by allocating memory if needed.
This commit is contained in:
Rich Felker 2013-08-02 09:56:49 -04:00
parent 7443dd271c
commit d5884a574c
1 changed files with 21 additions and 12 deletions
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33
src/ldso/dynlink.c
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@ -305,6 +305,7 @@ static void reclaim_gaps(unsigned char *base, Phdr *ph, size_t phent, size_t phc
static void *map_library(int fd, struct dso *dso) static void *map_library(int fd, struct dso *dso)
{ {
Ehdr buf[(896+sizeof(Ehdr))/sizeof(Ehdr)]; Ehdr buf[(896+sizeof(Ehdr))/sizeof(Ehdr)];
void *allocated_buf=0;
size_t phsize; size_t phsize;
size_t addr_min=SIZE_MAX, addr_max=0, map_len; size_t addr_min=SIZE_MAX, addr_max=0, map_len;
size_t this_min, this_max; size_t this_min, this_max;
@ -312,23 +313,28 @@ static void *map_library(int fd, struct dso *dso)
Ehdr *eh; Ehdr *eh;
Phdr *ph, *ph0; Phdr *ph, *ph0;
unsigned prot; unsigned prot;
unsigned char *map, *base; unsigned char *map=MAP_FAILED, *base;
size_t dyn=0; size_t dyn=0;
size_t tls_image=0; size_t tls_image=0;
size_t i; size_t i;
ssize_t l = read(fd, buf, sizeof buf); ssize_t l = read(fd, buf, sizeof buf);
if (l<(int)sizeof *eh) return 0;
eh = buf; eh = buf;
if (eh->e_type != ET_DYN && eh->e_type != ET_EXEC) { if (l<0) return 0;
errno = ENOEXEC; if (l<sizeof *eh || (eh->e_type != ET_DYN && eh->e_type != ET_EXEC))
return 0; goto noexec;
}
phsize = eh->e_phentsize * eh->e_phnum; phsize = eh->e_phentsize * eh->e_phnum;
if (phsize + sizeof *eh > l) return 0; if (phsize > sizeof buf - sizeof *eh) {
if (eh->e_phoff + phsize > l) { allocated_buf = malloc(phsize);
if (!allocated_buf) return 0;
l = pread(fd, allocated_buf, phsize, eh->e_phoff);
if (l < 0) goto error;
if (l != phsize) goto noexec;
ph = ph0 = allocated_buf;
} else if (eh->e_phoff + phsize > l) {
l = pread(fd, buf+1, phsize, eh->e_phoff); l = pread(fd, buf+1, phsize, eh->e_phoff);
if (l != phsize) return 0; if (l < 0) goto error;
if (l != phsize) goto noexec;
ph = ph0 = (void *)(buf + 1); ph = ph0 = (void *)(buf + 1);
} else { } else {
ph = ph0 = (void *)((char *)buf + eh->e_phoff); ph = ph0 = (void *)((char *)buf + eh->e_phoff);
@ -354,7 +360,7 @@ static void *map_library(int fd, struct dso *dso)
addr_max = ph->p_vaddr+ph->p_memsz; addr_max = ph->p_vaddr+ph->p_memsz;
} }
} }
if (!dyn) return 0; if (!dyn) goto noexec;
addr_max += PAGE_SIZE-1; addr_max += PAGE_SIZE-1;
addr_max &= -PAGE_SIZE; addr_max &= -PAGE_SIZE;
addr_min &= -PAGE_SIZE; addr_min &= -PAGE_SIZE;
@ -365,7 +371,7 @@ static void *map_library(int fd, struct dso *dso)
* use the invalid part; we just need to reserve the right * use the invalid part; we just need to reserve the right
* amount of virtual address space to map over later. */ * amount of virtual address space to map over later. */
map = mmap((void *)addr_min, map_len, prot, MAP_PRIVATE, fd, off_start); map = mmap((void *)addr_min, map_len, prot, MAP_PRIVATE, fd, off_start);
if (map==MAP_FAILED) return 0; if (map==MAP_FAILED) goto error;
/* If the loaded file is not relocatable and the requested address is /* If the loaded file is not relocatable and the requested address is
* not available, then the load operation must fail. */ * not available, then the load operation must fail. */
if (eh->e_type != ET_DYN && addr_min && map!=(void *)addr_min) { if (eh->e_type != ET_DYN && addr_min && map!=(void *)addr_min) {
@ -416,8 +422,11 @@ static void *map_library(int fd, struct dso *dso)
dso->dynv = (void *)(base+dyn); dso->dynv = (void *)(base+dyn);
if (dso->tls_size) dso->tls_image = (void *)(base+tls_image); if (dso->tls_size) dso->tls_image = (void *)(base+tls_image);
return map; return map;
noexec:
errno = ENOEXEC;
error: error:
munmap(map, map_len); if (map!=MAP_FAILED) munmap(map, map_len);
free(allocated_buf);
return 0; return 0;
} }