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authorMaciej W. Rozycki <macro@imgtec.com>2015-10-26 15:48:19 +0000
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2016-02-17 12:34:39 -0800
commitb9b99f7321d62f19bd90ddae27bc16ae05a07275 (patch)
parente4e5ae4ecc39575437c925b2f1f91a496c62d5c7 (diff)
binfmt_elf: Don't clobber passed executable's file header
commit b582ef5c53040c5feef4c96a8f9585b6831e2441 upstream. Do not clobber the buffer space passed from `search_binary_handler' and originally preloaded by `prepare_binprm' with the executable's file header by overwriting it with its interpreter's file header. Instead keep the buffer space intact and directly use the data structure locally allocated for the interpreter's file header, fixing a bug introduced in 2.1.14 with loadable module support (linux-mips.org commit beb11695 [Import of Linux/MIPS 2.1.14], predating kernel.org repo's history). Adjust the amount of data read from the interpreter's file accordingly. This was not an issue before loadable module support, because back then `load_elf_binary' was executed only once for a given ELF executable, whether the function succeeded or failed. With loadable module support supported and enabled, upon a failure of `load_elf_binary' -- which may for example be caused by architecture code rejecting an executable due to a missing hardware feature requested in the file header -- a module load is attempted and then the function reexecuted by `search_binary_handler'. With the executable's file header replaced with its interpreter's file header the executable can then be erroneously accepted in this subsequent attempt. Signed-off-by: Maciej W. Rozycki <macro@imgtec.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
1 files changed, 5 insertions, 5 deletions
diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index 35240a704413..6eb8df76e17c 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -679,16 +679,16 @@ static int load_elf_binary(struct linux_binprm *bprm)
would_dump(bprm, interpreter);
- retval = kernel_read(interpreter, 0, bprm->buf,
- if (retval != BINPRM_BUF_SIZE) {
+ /* Get the exec headers */
+ retval = kernel_read(interpreter, 0,
+ (void *)&loc->interp_elf_ex,
+ sizeof(loc->interp_elf_ex));
+ if (retval != sizeof(loc->interp_elf_ex)) {
if (retval >= 0)
retval = -EIO;
goto out_free_dentry;
- /* Get the exec headers */
- loc->interp_elf_ex = *((struct elfhdr *)bprm->buf);