From: Ernie Petrides Hi, Chuck. I did the RHEL3 and RHEL4 versions of those fixes, and I was waiting for 2.6.17 to be released before testing and posting the changes upstream (and I've been tied up this week and so hadn't gotten around to it yet). For background, the BAD_ADDR() macro should return TRUE if the address is TASK_SIZE, because that's the lowest address that is *not* valid for user-space mappings. The macro was correct in binfmt_aout.c but was wrong for the "equal to" case in binfmt_elf.c. There were two in-line validations of user-space addresses in binfmt_elf.c, which have been appropriately converted to use the corrected BAD_ADDR() macro in the patch you posted yesterday. Note that the size checks against TASK_SIZE are okay as coded. The additional changes that I propose are below. These are in the error paths for bad ELF entry addresses once load_elf_binary() has already committed to exec'ing the new image (following the tearing down of the task's original address space). The 1st hunk deals with the interp-side of the outer "if". There were two problems here. The printk() should be removed because this path can be triggered at will by a bogus interpreter image created and used by a malicious user. Further, the error code should not be ENOEXEC, because that causes the loop in search_binary_handler() to continue trying other exec handlers (twice, in fact). But it's too late for this to work correctly, because the user address space has already been torn down, and an exec() failure cannot be returned to the user code because the code no longer exists. The only recovery is to force a SIGSEGV, but it's best to terminate the search loop immediately. I somewhat arbitrarily chose EINVAL as a fallback error code, but any error returned by load_elf_interp() will override that (but this value will never be seen by user-space). The 2nd hunk deals with the non-interp-side of the outer "if". There were two problems here as well. The SIGSEGV needs to be forced, because a prior sigaction() syscall might have set the associated disposition to SIG_IGN. And the ENOEXEC should be changed to EINVAL as described above. Signed-off-by: Ernie Petrides Cc: Chuck Ebbert <76306.1226@compuserve.com> Signed-off-by: Andrew Morton --- fs/binfmt_elf.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) diff -puN fs/binfmt_elf.c~binfmt_elf-fix-checks-for-bad-address-fix fs/binfmt_elf.c --- a/fs/binfmt_elf.c~binfmt_elf-fix-checks-for-bad-address-fix +++ a/fs/binfmt_elf.c @@ -941,10 +941,9 @@ static int load_elf_binary(struct linux_ interpreter, &interp_load_addr); if (BAD_ADDR(elf_entry)) { - printk(KERN_ERR "Unable to load interpreter %.128s\n", - elf_interpreter); force_sig(SIGSEGV, current); - retval = -ENOEXEC; /* Nobody gets to see this, but.. */ + retval = IS_ERR((void *)elf_entry) ? + (int)elf_entry : -EINVAL; goto out_free_dentry; } reloc_func_desc = interp_load_addr; @@ -955,8 +954,8 @@ static int load_elf_binary(struct linux_ } else { elf_entry = loc->elf_ex.e_entry; if (BAD_ADDR(elf_entry)) { - send_sig(SIGSEGV, current, 0); - retval = -ENOEXEC; /* Nobody gets to see this, but.. */ + force_sig(SIGSEGV, current); + retval = -EINVAL; goto out_free_dentry; } } _