From 6e572ffe3feb8a02ed0044987654e07670aeffc2 Mon Sep 17 00:00:00 2001 From: Nicolas Pitre Date: Sun, 24 Jul 2016 11:30:21 -0400 Subject: [PATCH] binfmt_flat: use proper user space accessors with relocs processing code Relocs are fixed up in place in user space memory. The appropriate accessors are required for this code to work with an active MMU. The architecture specific handlers flat_get_addr_from_rp() and flat_put_addr_at_rp() for ARM and M68K are adjusted with separate patches. SuperH and Xtensa are left out as they doesn't implement __get_user_unaligned() and __put_user_unaligned() yet. The other architectures that use BFLT don't have any MMU. Signed-off-by: Nicolas Pitre Reviewed-by: Greg Ungerer Signed-off-by: Greg Ungerer --- fs/binfmt_flat.c | 31 +++++++++++++++++++------------ 1 file changed, 19 insertions(+), 12 deletions(-) diff --git a/fs/binfmt_flat.c b/fs/binfmt_flat.c index 5dc7968a424f..9deafb282db5 100644 --- a/fs/binfmt_flat.c +++ b/fs/binfmt_flat.c @@ -419,7 +419,7 @@ static int load_flat_file(struct linux_binprm *bprm, unsigned long textpos, datapos, realdatastart; unsigned long text_len, data_len, bss_len, stack_len, full_data, flags; unsigned long len, memp, memp_size, extra, rlim; - unsigned long *reloc, *rp; + unsigned long __user *reloc, *rp; struct inode *inode; int i, rev, relocs; loff_t fpos; @@ -591,7 +591,7 @@ static int load_flat_file(struct linux_binprm *bprm, goto err; } - reloc = (unsigned long *) + reloc = (unsigned long __user *) (datapos + (ntohl(hdr->reloc_start) - text_len)); memp = realdatastart; memp_size = len; @@ -616,7 +616,7 @@ static int load_flat_file(struct linux_binprm *bprm, MAX_SHARED_LIBS * sizeof(unsigned long), FLAT_DATA_ALIGN); - reloc = (unsigned long *) + reloc = (unsigned long __user *) (datapos + (ntohl(hdr->reloc_start) - text_len)); memp = textpos; memp_size = len; @@ -708,15 +708,20 @@ static int load_flat_file(struct linux_binprm *bprm, * image. */ if (flags & FLAT_FLAG_GOTPIC) { - for (rp = (unsigned long *)datapos; *rp != 0xffffffff; rp++) { - unsigned long addr; - if (*rp) { - addr = calc_reloc(*rp, libinfo, id, 0); + for (rp = (unsigned long __user *)datapos; ; rp++) { + unsigned long addr, rp_val; + if (get_user(rp_val, rp)) + return -EFAULT; + if (rp_val == 0xffffffff) + break; + if (rp_val) { + addr = calc_reloc(rp_val, libinfo, id, 0); if (addr == RELOC_FAILED) { ret = -ENOEXEC; goto err; } - *rp = addr; + if (put_user(addr, rp)) + return -EFAULT; } } } @@ -733,7 +738,7 @@ static int load_flat_file(struct linux_binprm *bprm, * __start to address 4 so that is okay). */ if (rev > OLD_FLAT_VERSION) { - unsigned long persistent = 0; + unsigned long __maybe_unused persistent = 0; for (i = 0; i < relocs; i++) { unsigned long addr, relval; @@ -742,12 +747,14 @@ static int load_flat_file(struct linux_binprm *bprm, * relocated (of course, the address has to be * relocated first). */ - relval = ntohl(reloc[i]); + if (get_user(relval, reloc + i)) + return -EFAULT; + relval = ntohl(relval); if (flat_set_persistent(relval, &persistent)) continue; addr = flat_get_relocate_addr(relval); - rp = (unsigned long *) calc_reloc(addr, libinfo, id, 1); - if (rp == (unsigned long *)RELOC_FAILED) { + rp = (unsigned long __user *)calc_reloc(addr, libinfo, id, 1); + if (rp == (unsigned long __user *)RELOC_FAILED) { ret = -ENOEXEC; goto err; } -- 2.20.1