FAILED: patch "[PATCH] smb: client: Fix use-after-free in cifs_fill_dirent" failed to apply to 5.15-stable tree
The patch below does not apply to the 5.15-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
To reproduce the conflict and resubmit, you may use the following commands:
git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y git checkout FETCH_HEAD git cherry-pick -x a7a8fe56e932a36f43e031b398aef92341bf5ea0 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2025052432-deafening-parted-13e0@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^..
Possible dependencies:
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From a7a8fe56e932a36f43e031b398aef92341bf5ea0 Mon Sep 17 00:00:00 2001 From: Wang Zhaolong wangzhaolong1@huawei.com Date: Fri, 16 May 2025 17:12:55 +0800 Subject: [PATCH] smb: client: Fix use-after-free in cifs_fill_dirent
There is a race condition in the readdir concurrency process, which may access the rsp buffer after it has been released, triggering the following KASAN warning.
================================================================== BUG: KASAN: slab-use-after-free in cifs_fill_dirent+0xb03/0xb60 [cifs] Read of size 4 at addr ffff8880099b819c by task a.out/342975
CPU: 2 UID: 0 PID: 342975 Comm: a.out Not tainted 6.15.0-rc6+ #240 PREEMPT(full) Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.1-2.fc37 04/01/2014 Call Trace: <TASK> dump_stack_lvl+0x53/0x70 print_report+0xce/0x640 kasan_report+0xb8/0xf0 cifs_fill_dirent+0xb03/0xb60 [cifs] cifs_readdir+0x12cb/0x3190 [cifs] iterate_dir+0x1a1/0x520 __x64_sys_getdents+0x134/0x220 do_syscall_64+0x4b/0x110 entry_SYSCALL_64_after_hwframe+0x76/0x7e RIP: 0033:0x7f996f64b9f9 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0d f7 c3 0c 00 f7 d8 64 89 8 RSP: 002b:00007f996f53de78 EFLAGS: 00000207 ORIG_RAX: 000000000000004e RAX: ffffffffffffffda RBX: 00007f996f53ecdc RCX: 00007f996f64b9f9 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003 RBP: 00007f996f53dea0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000207 R12: ffffffffffffff88 R13: 0000000000000000 R14: 00007ffc8cd9a500 R15: 00007f996f51e000 </TASK>
Allocated by task 408: kasan_save_stack+0x20/0x40 kasan_save_track+0x14/0x30 __kasan_slab_alloc+0x6e/0x70 kmem_cache_alloc_noprof+0x117/0x3d0 mempool_alloc_noprof+0xf2/0x2c0 cifs_buf_get+0x36/0x80 [cifs] allocate_buffers+0x1d2/0x330 [cifs] cifs_demultiplex_thread+0x22b/0x2690 [cifs] kthread+0x394/0x720 ret_from_fork+0x34/0x70 ret_from_fork_asm+0x1a/0x30
Freed by task 342979: kasan_save_stack+0x20/0x40 kasan_save_track+0x14/0x30 kasan_save_free_info+0x3b/0x60 __kasan_slab_free+0x37/0x50 kmem_cache_free+0x2b8/0x500 cifs_buf_release+0x3c/0x70 [cifs] cifs_readdir+0x1c97/0x3190 [cifs] iterate_dir+0x1a1/0x520 __x64_sys_getdents64+0x134/0x220 do_syscall_64+0x4b/0x110 entry_SYSCALL_64_after_hwframe+0x76/0x7e
The buggy address belongs to the object at ffff8880099b8000 which belongs to the cache cifs_request of size 16588 The buggy address is located 412 bytes inside of freed 16588-byte region [ffff8880099b8000, ffff8880099bc0cc)
The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x99b8 head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0 anon flags: 0x80000000000040(head|node=0|zone=1) page_type: f5(slab) raw: 0080000000000040 ffff888001e03400 0000000000000000 dead000000000001 raw: 0000000000000000 0000000000010001 00000000f5000000 0000000000000000 head: 0080000000000040 ffff888001e03400 0000000000000000 dead000000000001 head: 0000000000000000 0000000000010001 00000000f5000000 0000000000000000 head: 0080000000000003 ffffea0000266e01 00000000ffffffff 00000000ffffffff head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000008 page dumped because: kasan: bad access detected
Memory state around the buggy address: ffff8880099b8080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8880099b8100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8880099b8180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^ ffff8880099b8200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8880099b8280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================
POC is available in the link [1].
The problem triggering process is as follows:
Process 1 Process 2 ----------------------------------------------------------------- cifs_readdir /* file->private_data == NULL */ initiate_cifs_search cifsFile = kzalloc(sizeof(struct cifsFileInfo), GFP_KERNEL); smb2_query_dir_first ->query_dir_first() SMB2_query_directory SMB2_query_directory_init cifs_send_recv smb2_parse_query_directory srch_inf->ntwrk_buf_start = (char *)rsp; srch_inf->srch_entries_start = (char *)rsp + ... srch_inf->last_entry = (char *)rsp + ... srch_inf->smallBuf = true; find_cifs_entry /* if (cfile->srch_inf.ntwrk_buf_start) */ cifs_small_buf_release(cfile->srch_inf // free
cifs_readdir ->iterate_shared() /* file->private_data != NULL */ find_cifs_entry /* in while (...) loop */ smb2_query_dir_next ->query_dir_next() SMB2_query_directory SMB2_query_directory_init cifs_send_recv compound_send_recv smb_send_rqst __smb_send_rqst rc = -ERESTARTSYS; /* if (fatal_signal_pending()) */ goto out; return rc /* if (cfile->srch_inf.last_entry) */ cifs_save_resume_key() cifs_fill_dirent // UAF /* if (rc) */ return -ENOENT;
Fix this by ensuring the return code is checked before using pointers from the srch_inf.
Link: https://bugzilla.kernel.org/show_bug.cgi?id=220131 [1] Fixes: a364bc0b37f1 ("[CIFS] fix saving of resume key before CIFSFindNext") Cc: stable@vger.kernel.org Reviewed-by: Paulo Alcantara (Red Hat) pc@manguebit.com Signed-off-by: Wang Zhaolong wangzhaolong1@huawei.com Signed-off-by: Steve French stfrench@microsoft.com
diff --git a/fs/smb/client/readdir.c b/fs/smb/client/readdir.c index 50f96259d9ad..67d7dd64b5e2 100644 --- a/fs/smb/client/readdir.c +++ b/fs/smb/client/readdir.c @@ -756,11 +756,11 @@ find_cifs_entry(const unsigned int xid, struct cifs_tcon *tcon, loff_t pos, rc = server->ops->query_dir_next(xid, tcon, &cfile->fid, search_flags, &cfile->srch_inf); + if (rc) + return -ENOENT; /* FindFirst/Next set last_entry to NULL on malformed reply */ if (cfile->srch_inf.last_entry) cifs_save_resume_key(cfile->srch_inf.last_entry, cfile); - if (rc) - return -ENOENT; } if (index_to_find < cfile->srch_inf.index_of_last_entry) { /* we found the buffer that contains the entry */
There is a race condition in the readdir concurrency process, which may access the rsp buffer after it has been released, triggering the following KASAN warning.
================================================================== BUG: KASAN: slab-use-after-free in cifs_fill_dirent+0xb03/0xb60 [cifs] Read of size 4 at addr ffff8880099b819c by task a.out/342975
CPU: 2 UID: 0 PID: 342975 Comm: a.out Not tainted 6.15.0-rc6+ #240 PREEMPT(full) Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.1-2.fc37 04/01/2014 Call Trace: <TASK> dump_stack_lvl+0x53/0x70 print_report+0xce/0x640 kasan_report+0xb8/0xf0 cifs_fill_dirent+0xb03/0xb60 [cifs] cifs_readdir+0x12cb/0x3190 [cifs] iterate_dir+0x1a1/0x520 __x64_sys_getdents+0x134/0x220 do_syscall_64+0x4b/0x110 entry_SYSCALL_64_after_hwframe+0x76/0x7e RIP: 0033:0x7f996f64b9f9 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0d f7 c3 0c 00 f7 d8 64 89 8 RSP: 002b:00007f996f53de78 EFLAGS: 00000207 ORIG_RAX: 000000000000004e RAX: ffffffffffffffda RBX: 00007f996f53ecdc RCX: 00007f996f64b9f9 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003 RBP: 00007f996f53dea0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000207 R12: ffffffffffffff88 R13: 0000000000000000 R14: 00007ffc8cd9a500 R15: 00007f996f51e000 </TASK>
Allocated by task 408: kasan_save_stack+0x20/0x40 kasan_save_track+0x14/0x30 __kasan_slab_alloc+0x6e/0x70 kmem_cache_alloc_noprof+0x117/0x3d0 mempool_alloc_noprof+0xf2/0x2c0 cifs_buf_get+0x36/0x80 [cifs] allocate_buffers+0x1d2/0x330 [cifs] cifs_demultiplex_thread+0x22b/0x2690 [cifs] kthread+0x394/0x720 ret_from_fork+0x34/0x70 ret_from_fork_asm+0x1a/0x30
Freed by task 342979: kasan_save_stack+0x20/0x40 kasan_save_track+0x14/0x30 kasan_save_free_info+0x3b/0x60 __kasan_slab_free+0x37/0x50 kmem_cache_free+0x2b8/0x500 cifs_buf_release+0x3c/0x70 [cifs] cifs_readdir+0x1c97/0x3190 [cifs] iterate_dir+0x1a1/0x520 __x64_sys_getdents64+0x134/0x220 do_syscall_64+0x4b/0x110 entry_SYSCALL_64_after_hwframe+0x76/0x7e
The buggy address belongs to the object at ffff8880099b8000 which belongs to the cache cifs_request of size 16588 The buggy address is located 412 bytes inside of freed 16588-byte region [ffff8880099b8000, ffff8880099bc0cc)
The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x99b8 head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0 anon flags: 0x80000000000040(head|node=0|zone=1) page_type: f5(slab) raw: 0080000000000040 ffff888001e03400 0000000000000000 dead000000000001 raw: 0000000000000000 0000000000010001 00000000f5000000 0000000000000000 head: 0080000000000040 ffff888001e03400 0000000000000000 dead000000000001 head: 0000000000000000 0000000000010001 00000000f5000000 0000000000000000 head: 0080000000000003 ffffea0000266e01 00000000ffffffff 00000000ffffffff head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000008 page dumped because: kasan: bad access detected
Memory state around the buggy address: ffff8880099b8080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8880099b8100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8880099b8180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^ ffff8880099b8200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8880099b8280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================
POC is available in the link [1].
The problem triggering process is as follows:
Process 1 Process 2 ----------------------------------------------------------------- cifs_readdir /* file->private_data == NULL */ initiate_cifs_search cifsFile = kzalloc(sizeof(struct cifsFileInfo), GFP_KERNEL); smb2_query_dir_first ->query_dir_first() SMB2_query_directory SMB2_query_directory_init cifs_send_recv smb2_parse_query_directory srch_inf->ntwrk_buf_start = (char *)rsp; srch_inf->srch_entries_start = (char *)rsp + ... srch_inf->last_entry = (char *)rsp + ... srch_inf->smallBuf = true; find_cifs_entry /* if (cfile->srch_inf.ntwrk_buf_start) */ cifs_small_buf_release(cfile->srch_inf // free
cifs_readdir ->iterate_shared() /* file->private_data != NULL */ find_cifs_entry /* in while (...) loop */ smb2_query_dir_next ->query_dir_next() SMB2_query_directory SMB2_query_directory_init cifs_send_recv compound_send_recv smb_send_rqst __smb_send_rqst rc = -ERESTARTSYS; /* if (fatal_signal_pending()) */ goto out; return rc /* if (cfile->srch_inf.last_entry) */ cifs_save_resume_key() cifs_fill_dirent // UAF /* if (rc) */ return -ENOENT;
Fix this by ensuring the return code is checked before using pointers from the srch_inf.
Link: https://bugzilla.kernel.org/show_bug.cgi?id=220131 [1] Fixes: a364bc0b37f1 ("[CIFS] fix saving of resume key before CIFSFindNext") Cc: stable@vger.kernel.org Reviewed-by: Paulo Alcantara (Red Hat) pc@manguebit.com Signed-off-by: Wang Zhaolong wangzhaolong1@huawei.com Signed-off-by: Steve French stfrench@microsoft.com (cherry picked from commit a7a8fe56e932a36f43e031b398aef92341bf5ea0) --- fs/cifs/readdir.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/fs/cifs/readdir.c b/fs/cifs/readdir.c index 1929e80c09ee..de6077ab7cd6 100644 --- a/fs/cifs/readdir.c +++ b/fs/cifs/readdir.c @@ -783,15 +783,15 @@ find_cifs_entry(const unsigned int xid, struct cifs_tcon *tcon, loff_t pos, (rc == 0) && !cfile->srch_inf.endOfSearch) { cifs_dbg(FYI, "calling findnext2\n"); rc = server->ops->query_dir_next(xid, tcon, &cfile->fid, search_flags, &cfile->srch_inf); + if (rc) + return -ENOENT; /* FindFirst/Next set last_entry to NULL on malformed reply */ if (cfile->srch_inf.last_entry) cifs_save_resume_key(cfile->srch_inf.last_entry, cfile); - if (rc) - return -ENOENT; } if (index_to_find < cfile->srch_inf.index_of_last_entry) { /* we found the buffer that contains the entry */ /* scan and find it */ int i;
Multiple pointers in struct cifs_search_info (ntwrk_buf_start, srch_entries_start, and last_entry) point to the same allocated buffer. However, when freeing this buffer, only ntwrk_buf_start was set to NULL, while the other pointers remained pointing to freed memory.
This is defensive programming to prevent potential issues with stale pointers. While the active UAF vulnerability is fixed by the previous patch, this change ensures consistent pointer state and more robust error handling.
Signed-off-by: Wang Zhaolong wangzhaolong1@huawei.com Cc: stable@vger.kernel.org Reviewed-by: Paulo Alcantara (Red Hat) pc@manguebit.com Signed-off-by: Steve French stfrench@microsoft.com (cherry picked from commit e48f9d849bfdec276eebf782a84fd4dfbe1c14c0) --- fs/cifs/readdir.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/fs/cifs/readdir.c b/fs/cifs/readdir.c index de6077ab7cd6..6aa3c267f4ca 100644 --- a/fs/cifs/readdir.c +++ b/fs/cifs/readdir.c @@ -760,11 +760,14 @@ find_cifs_entry(const unsigned int xid, struct cifs_tcon *tcon, loff_t pos, cifs_small_buf_release(cfile->srch_inf. ntwrk_buf_start); else cifs_buf_release(cfile->srch_inf. ntwrk_buf_start); + /* Reset all pointers to the network buffer to prevent stale references */ cfile->srch_inf.ntwrk_buf_start = NULL; + cfile->srch_inf.srch_entries_start = NULL; + cfile->srch_inf.last_entry = NULL; } rc = initiate_cifs_search(xid, file, full_path); if (rc) { cifs_dbg(FYI, "error %d reinitiating a search on rewind\n", rc);
There is a race condition in the readdir concurrency process, which may access the rsp buffer after it has been released, triggering the following KASAN warning.
================================================================== BUG: KASAN: slab-use-after-free in cifs_fill_dirent+0xb03/0xb60 [cifs] Read of size 4 at addr ffff8880099b819c by task a.out/342975
CPU: 2 UID: 0 PID: 342975 Comm: a.out Not tainted 6.15.0-rc6+ #240 PREEMPT(full) Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.1-2.fc37 04/01/2014 Call Trace: <TASK> dump_stack_lvl+0x53/0x70 print_report+0xce/0x640 kasan_report+0xb8/0xf0 cifs_fill_dirent+0xb03/0xb60 [cifs] cifs_readdir+0x12cb/0x3190 [cifs] iterate_dir+0x1a1/0x520 __x64_sys_getdents+0x134/0x220 do_syscall_64+0x4b/0x110 entry_SYSCALL_64_after_hwframe+0x76/0x7e RIP: 0033:0x7f996f64b9f9 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0d f7 c3 0c 00 f7 d8 64 89 8 RSP: 002b:00007f996f53de78 EFLAGS: 00000207 ORIG_RAX: 000000000000004e RAX: ffffffffffffffda RBX: 00007f996f53ecdc RCX: 00007f996f64b9f9 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003 RBP: 00007f996f53dea0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000207 R12: ffffffffffffff88 R13: 0000000000000000 R14: 00007ffc8cd9a500 R15: 00007f996f51e000 </TASK>
Allocated by task 408: kasan_save_stack+0x20/0x40 kasan_save_track+0x14/0x30 __kasan_slab_alloc+0x6e/0x70 kmem_cache_alloc_noprof+0x117/0x3d0 mempool_alloc_noprof+0xf2/0x2c0 cifs_buf_get+0x36/0x80 [cifs] allocate_buffers+0x1d2/0x330 [cifs] cifs_demultiplex_thread+0x22b/0x2690 [cifs] kthread+0x394/0x720 ret_from_fork+0x34/0x70 ret_from_fork_asm+0x1a/0x30
Freed by task 342979: kasan_save_stack+0x20/0x40 kasan_save_track+0x14/0x30 kasan_save_free_info+0x3b/0x60 __kasan_slab_free+0x37/0x50 kmem_cache_free+0x2b8/0x500 cifs_buf_release+0x3c/0x70 [cifs] cifs_readdir+0x1c97/0x3190 [cifs] iterate_dir+0x1a1/0x520 __x64_sys_getdents64+0x134/0x220 do_syscall_64+0x4b/0x110 entry_SYSCALL_64_after_hwframe+0x76/0x7e
The buggy address belongs to the object at ffff8880099b8000 which belongs to the cache cifs_request of size 16588 The buggy address is located 412 bytes inside of freed 16588-byte region [ffff8880099b8000, ffff8880099bc0cc)
The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x99b8 head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0 anon flags: 0x80000000000040(head|node=0|zone=1) page_type: f5(slab) raw: 0080000000000040 ffff888001e03400 0000000000000000 dead000000000001 raw: 0000000000000000 0000000000010001 00000000f5000000 0000000000000000 head: 0080000000000040 ffff888001e03400 0000000000000000 dead000000000001 head: 0000000000000000 0000000000010001 00000000f5000000 0000000000000000 head: 0080000000000003 ffffea0000266e01 00000000ffffffff 00000000ffffffff head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000008 page dumped because: kasan: bad access detected
Memory state around the buggy address: ffff8880099b8080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8880099b8100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8880099b8180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^ ffff8880099b8200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8880099b8280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================
POC is available in the link [1].
The problem triggering process is as follows:
Process 1 Process 2 ----------------------------------------------------------------- cifs_readdir /* file->private_data == NULL */ initiate_cifs_search cifsFile = kzalloc(sizeof(struct cifsFileInfo), GFP_KERNEL); smb2_query_dir_first ->query_dir_first() SMB2_query_directory SMB2_query_directory_init cifs_send_recv smb2_parse_query_directory srch_inf->ntwrk_buf_start = (char *)rsp; srch_inf->srch_entries_start = (char *)rsp + ... srch_inf->last_entry = (char *)rsp + ... srch_inf->smallBuf = true; find_cifs_entry /* if (cfile->srch_inf.ntwrk_buf_start) */ cifs_small_buf_release(cfile->srch_inf // free
cifs_readdir ->iterate_shared() /* file->private_data != NULL */ find_cifs_entry /* in while (...) loop */ smb2_query_dir_next ->query_dir_next() SMB2_query_directory SMB2_query_directory_init cifs_send_recv compound_send_recv smb_send_rqst __smb_send_rqst rc = -ERESTARTSYS; /* if (fatal_signal_pending()) */ goto out; return rc /* if (cfile->srch_inf.last_entry) */ cifs_save_resume_key() cifs_fill_dirent // UAF /* if (rc) */ return -ENOENT;
Fix this by ensuring the return code is checked before using pointers from the srch_inf.
Link: https://bugzilla.kernel.org/show_bug.cgi?id=220131 [1] Fixes: a364bc0b37f1 ("[CIFS] fix saving of resume key before CIFSFindNext") Cc: stable@vger.kernel.org Reviewed-by: Paulo Alcantara (Red Hat) pc@manguebit.com Signed-off-by: Wang Zhaolong wangzhaolong1@huawei.com Signed-off-by: Steve French stfrench@microsoft.com (cherry picked from commit a7a8fe56e932a36f43e031b398aef92341bf5ea0) Signed-off-by: Wang Zhaolong wangzhaolong1@huawei.com --- fs/cifs/readdir.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/fs/cifs/readdir.c b/fs/cifs/readdir.c index 1929e80c09ee..de6077ab7cd6 100644 --- a/fs/cifs/readdir.c +++ b/fs/cifs/readdir.c @@ -783,15 +783,15 @@ find_cifs_entry(const unsigned int xid, struct cifs_tcon *tcon, loff_t pos, (rc == 0) && !cfile->srch_inf.endOfSearch) { cifs_dbg(FYI, "calling findnext2\n"); rc = server->ops->query_dir_next(xid, tcon, &cfile->fid, search_flags, &cfile->srch_inf); + if (rc) + return -ENOENT; /* FindFirst/Next set last_entry to NULL on malformed reply */ if (cfile->srch_inf.last_entry) cifs_save_resume_key(cfile->srch_inf.last_entry, cfile); - if (rc) - return -ENOENT; } if (index_to_find < cfile->srch_inf.index_of_last_entry) { /* we found the buffer that contains the entry */ /* scan and find it */ int i;
Multiple pointers in struct cifs_search_info (ntwrk_buf_start, srch_entries_start, and last_entry) point to the same allocated buffer. However, when freeing this buffer, only ntwrk_buf_start was set to NULL, while the other pointers remained pointing to freed memory.
This is defensive programming to prevent potential issues with stale pointers. While the active UAF vulnerability is fixed by the previous patch, this change ensures consistent pointer state and more robust error handling.
Signed-off-by: Wang Zhaolong wangzhaolong1@huawei.com Cc: stable@vger.kernel.org Reviewed-by: Paulo Alcantara (Red Hat) pc@manguebit.com Signed-off-by: Steve French stfrench@microsoft.com (cherry picked from commit e48f9d849bfdec276eebf782a84fd4dfbe1c14c0) Signed-off-by: Wang Zhaolong wangzhaolong1@huawei.com --- fs/cifs/readdir.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/fs/cifs/readdir.c b/fs/cifs/readdir.c index de6077ab7cd6..6aa3c267f4ca 100644 --- a/fs/cifs/readdir.c +++ b/fs/cifs/readdir.c @@ -760,11 +760,14 @@ find_cifs_entry(const unsigned int xid, struct cifs_tcon *tcon, loff_t pos, cifs_small_buf_release(cfile->srch_inf. ntwrk_buf_start); else cifs_buf_release(cfile->srch_inf. ntwrk_buf_start); + /* Reset all pointers to the network buffer to prevent stale references */ cfile->srch_inf.ntwrk_buf_start = NULL; + cfile->srch_inf.srch_entries_start = NULL; + cfile->srch_inf.last_entry = NULL; } rc = initiate_cifs_search(xid, file, full_path); if (rc) { cifs_dbg(FYI, "error %d reinitiating a search on rewind\n", rc);
linux-stable-mirror@lists.linaro.org
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gregkh＠linuxfoundation.org -
Wang Zhaolong