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SubjectRe: Kernel Oops on locking sockets via fcntl()

This should fix the bug, there were some cases outside
of file locking (bonus points to anyone who can craft
an exploit for the ELF interpreter case :-):

--- ./fs/binfmt_elf.c.~1~ Mon Oct 30 11:34:25 2000
+++ ./fs/binfmt_elf.c Tue Nov 28 03:03:43 2000
@@ -247,7 +247,7 @@
goto out;
if (!elf_check_arch(interp_elf_ex))
goto out;
- if (!interpreter->f_op->mmap)
+ if (!interpreter->f_op || !interpreter->f_op->mmap)
goto out;

/*
@@ -364,7 +364,7 @@

do_brk(0, text_data);
retval = -ENOEXEC;
- if (!interpreter->f_op->read)
+ if (!interpreter->f_op || !interpreter->f_op->read)
goto out;
retval = interpreter->f_op->read(interpreter, addr, text_data, &offset);
if (retval < 0)
@@ -789,7 +789,7 @@

/* First of all, some simple consistency checks */
if (elf_ex.e_type != ET_EXEC || elf_ex.e_phnum > 2 ||
- !elf_check_arch(&elf_ex) || !file->f_op->mmap)
+ !elf_check_arch(&elf_ex) || !file->f_op || !file->f_op->mmap)
goto out;

/* Now read in all of the header information */
--- ./fs/dquot.c.~1~ Fri Nov 17 17:24:03 2000
+++ ./fs/dquot.c Tue Nov 28 03:05:43 2000
@@ -1474,7 +1474,7 @@
if (IS_ERR(f))
goto out_lock;
error = -EIO;
- if (!f->f_op->read && !f->f_op->write)
+ if (!f->f_op || (!f->f_op->read && !f->f_op->write))
goto out_f;
inode = f->f_dentry->d_inode;
error = -EACCES;
--- ./fs/exec.c.~1~ Thu Nov 9 20:44:59 2000
+++ ./fs/exec.c Tue Nov 28 03:15:42 2000
@@ -604,6 +604,8 @@
/* Huh? We had already checked for MAY_EXEC, WTF do we check this? */
if (!(mode & 0111)) /* with at least _one_ execute bit set */
return -EACCES;
+ if (bprm->file->f_op == NULL)
+ return -EACCES;

bprm->e_uid = current->euid;
bprm->e_gid = current->egid;
--- ./fs/locks.c.~1~ Tue Nov 7 21:04:51 2000
+++ ./fs/locks.c Tue Nov 28 03:13:34 2000
@@ -511,7 +511,8 @@
struct file_lock *fl = *thisfl_p;
int (*lock)(struct file *, int, struct file_lock *);

- if ((lock = fl->fl_file->f_op->lock) != NULL) {
+ if (fl->fl_file->f_op &&
+ (lock = fl->fl_file->f_op->lock) != NULL) {
fl->fl_type = F_UNLCK;
lock(fl->fl_file, F_SETLK, fl);
}
@@ -1355,7 +1356,7 @@
if (!flock_to_posix_lock(filp, &file_lock, &flock))
goto out_putf;

- if (filp->f_op->lock) {
+ if (filp->f_op && filp->f_op->lock) {
error = filp->f_op->lock(filp, F_GETLK, &file_lock);
if (error < 0)
goto out_putf;
@@ -1479,7 +1480,7 @@
goto out_putf;
}

- if (filp->f_op->lock != NULL) {
+ if (filp->f_op && filp->f_op->lock != NULL) {
error = filp->f_op->lock(filp, cmd, file_lock);
if (error < 0)
goto out_putf;
@@ -1520,7 +1521,7 @@
if (!flock64_to_posix_lock(filp, &file_lock, &flock))
goto out_putf;

- if (filp->f_op->lock) {
+ if (filp->f_op && filp->f_op->lock) {
error = filp->f_op->lock(filp, F_GETLK, &file_lock);
if (error < 0)
goto out_putf;
@@ -1617,7 +1618,7 @@
goto out_putf;
}

- if (filp->f_op->lock != NULL) {
+ if (filp->f_op && filp->f_op->lock != NULL) {
error = filp->f_op->lock(filp, cmd, file_lock);
if (error < 0)
goto out_putf;
-
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