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Filipe Manana e60aa5da14 btrfs: refresh dir last index during a rewinddir(3) call 
When opening a directory we find what's the index of its last entry and
then store it in the directory's file handle private data (struct
btrfs_file_private::last_index), so that in the case new directory entries
are added to a directory after an opendir(3) call we don't end up in an
infinite loop (see commit 9b378f6ad4 ("btrfs: fix infinite directory
reads")) when calling readdir(3).

However once rewinddir(3) is called, POSIX states [1] that any new
directory entries added after the previous opendir(3) call, must be
returned by subsequent calls to readdir(3):

  "The rewinddir() function shall reset the position of the directory
   stream to which dirp refers to the beginning of the directory.
   It shall also cause the directory stream to refer to the current
   state of the corresponding directory, as a call to opendir() would
   have done."

We currently don't refresh the last_index field of the struct
btrfs_file_private associated to the directory, so after a rewinddir(3)
we are not returning any new entries added after the opendir(3) call.

Fix this by finding the current last index of the directory when llseek
is called against the directory.

This can be reproduced by the following C program provided by Ian Johnson:

   #include <dirent.h>
   #include <stdio.h>

   int main(void) {
     DIR *dir = opendir("test");

     FILE *file;
     file = fopen("test/1", "w");
     fwrite("1", 1, 1, file);
     fclose(file);

     file = fopen("test/2", "w");
     fwrite("2", 1, 1, file);
     fclose(file);

     rewinddir(dir);

     struct dirent *entry;
     while ((entry = readdir(dir))) {
        printf("%s\n", entry->d_name);
     }
     closedir(dir);
     return 0;
   }

Reported-by: Ian Johnson <ian@ianjohnson.dev>
Link: https://lore.kernel.org/linux-btrfs/YR1P0S.NGASEG570GJ8@ianjohnson.dev/
Fixes: 9b378f6ad4 ("btrfs: fix infinite directory reads")
CC: stable@vger.kernel.org # 6.5+
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2023-09-14 23:24:42 +02:00
arch - Use LEA ...%rsp instead of ADD %rsp in the Zen1/2 SRSO return sequence 2023-08-19 10:46:02 +02:00
block block-6.5-2023-08-19 2023-08-19 17:31:46 +02:00
certs KEYS: Add missing function documentation 2023-04-24 16:15:52 +03:00
crypto crypto: algif_hash - Fix race between MORE and non-MORE sends 2023-07-08 22:48:42 +10:00
Documentation MAINTAINERS: remove links to obsolete btrfs.wiki.kernel.org 2023-09-08 14:21:27 +02:00
drivers TTY/Serial fixes for 6.5-rc7 2023-08-20 08:26:51 +02:00
fs btrfs: refresh dir last index during a rewinddir(3) call 2023-09-14 23:24:42 +02:00
include btrfs: remove v0 extent handling 2023-08-21 14:54:48 +02:00
init Kbuild updates for v6.5 2023-07-01 09:24:31 -07:00
io_uring io_uring/parisc: Adjust pgoff in io_uring mmap() for parisc 2023-08-08 12:37:01 -06:00
ipc Merge branch 'work.namespace' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2023-02-24 19:20:07 -08:00
kernel Power management fixes for 6.5-rc6 2023-08-11 12:24:22 -07:00
lib 14 hotfixes. 11 of these are cc:stable and the remainder address post-6.4 2023-08-11 14:19:20 -07:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm mm: remove folio_account_redirty 2023-08-21 14:52:16 +02:00
net Including fixes from ipsec and netfilter. 2023-08-18 06:52:23 +02:00
rust rust: macros: vtable: fix HAS_* redefinition (gen_const_name) 2023-08-09 21:15:07 +02:00
samples arm64: ftrace: Add direct call trampoline samples support 2023-07-10 17:51:54 -04:00
scripts Kbuild fixes for v6.5 (2nd) 2023-08-13 08:56:24 -07:00
security sysctl: set variable key_sysctls storage-class-specifier to static 2023-08-07 17:55:54 +00:00
sound ALSA: hda/realtek - Remodified 3k pull low procedure 2023-08-16 14:20:27 +02:00
tools - Use LEA ...%rsp instead of ADD %rsp in the Zen1/2 SRSO return sequence 2023-08-19 10:46:02 +02:00
usr initramfs: Encode dependency on KBUILD_BUILD_TIMESTAMP 2023-06-06 17:54:49 +09:00
virt KVM: Grab a reference to KVM for VM and vCPU stats file descriptors 2023-07-29 11:05:28 -04:00
.clang-format iommu: Add for_each_group_device() 2023-05-23 08:15:51 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore Revert ".gitignore: ignore *.cover and *.mbx" 2023-07-04 15:05:12 -07:00
.mailmap mailmap: add entries for Simon Horman 2023-08-16 09:53:10 +01:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS - Address -Wmissing-prototype warnings 2023-06-26 16:43:54 -07:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS MAINTAINERS: remove links to obsolete btrfs.wiki.kernel.org 2023-09-08 14:21:27 +02:00
Makefile Linux 6.5-rc7 2023-08-20 15:02:52 +02:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.