* [Linux-kernel-mentees] [PATCH] hfs, hfsplus: Fix NULL pointer dereference in hfs_find_init() @ 2020-08-12 6:55 Peilin Ye 2020-08-12 7:08 ` Greg Kroah-Hartman 0 siblings, 1 reply; 10+ messages in thread From: Peilin Ye @ 2020-08-12 6:55 UTC (permalink / raw) Cc: syzkaller-bugs, linux-kernel, linux-fsdevel, linux-kernel-mentees, Peilin Ye Prevent hfs_find_init() from dereferencing `tree` as NULL. Reported-and-tested-by: syzbot+7ca256d0da4af073b2e2@syzkaller.appspotmail.com Signed-off-by: Peilin Ye <yepeilin.cs@gmail.com> --- fs/hfs/bfind.c | 3 +++ fs/hfsplus/bfind.c | 3 +++ 2 files changed, 6 insertions(+) diff --git a/fs/hfs/bfind.c b/fs/hfs/bfind.c index 4af318fbda77..880b7ea2c0fc 100644 --- a/fs/hfs/bfind.c +++ b/fs/hfs/bfind.c @@ -16,6 +16,9 @@ int hfs_find_init(struct hfs_btree *tree, struct hfs_find_data *fd) { void *ptr; + if (!tree) + return -EINVAL; + fd->tree = tree; fd->bnode = NULL; ptr = kmalloc(tree->max_key_len * 2 + 4, GFP_KERNEL); diff --git a/fs/hfsplus/bfind.c b/fs/hfsplus/bfind.c index ca2ba8c9f82e..85bef3e44d7a 100644 --- a/fs/hfsplus/bfind.c +++ b/fs/hfsplus/bfind.c @@ -16,6 +16,9 @@ int hfs_find_init(struct hfs_btree *tree, struct hfs_find_data *fd) { void *ptr; + if (!tree) + return -EINVAL; + fd->tree = tree; fd->bnode = NULL; ptr = kmalloc(tree->max_key_len * 2 + 4, GFP_KERNEL); -- 2.25.1 _______________________________________________ Linux-kernel-mentees mailing list Linux-kernel-mentees@lists.linuxfoundation.org https://lists.linuxfoundation.org/mailman/listinfo/linux-kernel-mentees ^ permalink raw reply related [flat|nested] 10+ messages in thread
* Re: [Linux-kernel-mentees] [PATCH] hfs, hfsplus: Fix NULL pointer dereference in hfs_find_init() 2020-08-12 6:55 [Linux-kernel-mentees] [PATCH] hfs, hfsplus: Fix NULL pointer dereference in hfs_find_init() Peilin Ye @ 2020-08-12 7:08 ` Greg Kroah-Hartman 2020-08-12 7:13 ` Peilin Ye 0 siblings, 1 reply; 10+ messages in thread From: Greg Kroah-Hartman @ 2020-08-12 7:08 UTC (permalink / raw) To: Peilin Ye Cc: linux-fsdevel, syzkaller-bugs, linux-kernel-mentees, linux-kernel On Wed, Aug 12, 2020 at 02:55:56AM -0400, Peilin Ye wrote: > Prevent hfs_find_init() from dereferencing `tree` as NULL. > > Reported-and-tested-by: syzbot+7ca256d0da4af073b2e2@syzkaller.appspotmail.com > Signed-off-by: Peilin Ye <yepeilin.cs@gmail.com> > --- > fs/hfs/bfind.c | 3 +++ > fs/hfsplus/bfind.c | 3 +++ > 2 files changed, 6 insertions(+) > > diff --git a/fs/hfs/bfind.c b/fs/hfs/bfind.c > index 4af318fbda77..880b7ea2c0fc 100644 > --- a/fs/hfs/bfind.c > +++ b/fs/hfs/bfind.c > @@ -16,6 +16,9 @@ int hfs_find_init(struct hfs_btree *tree, struct hfs_find_data *fd) > { > void *ptr; > > + if (!tree) > + return -EINVAL; > + > fd->tree = tree; > fd->bnode = NULL; > ptr = kmalloc(tree->max_key_len * 2 + 4, GFP_KERNEL); > diff --git a/fs/hfsplus/bfind.c b/fs/hfsplus/bfind.c > index ca2ba8c9f82e..85bef3e44d7a 100644 > --- a/fs/hfsplus/bfind.c > +++ b/fs/hfsplus/bfind.c > @@ -16,6 +16,9 @@ int hfs_find_init(struct hfs_btree *tree, struct hfs_find_data *fd) > { > void *ptr; > > + if (!tree) > + return -EINVAL; > + How can tree ever be NULL in these calls? Shouldn't that be fixed as the root problem here? thanks, greg k-h _______________________________________________ Linux-kernel-mentees mailing list Linux-kernel-mentees@lists.linuxfoundation.org https://lists.linuxfoundation.org/mailman/listinfo/linux-kernel-mentees ^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [Linux-kernel-mentees] [PATCH] hfs, hfsplus: Fix NULL pointer dereference in hfs_find_init() 2020-08-12 7:08 ` Greg Kroah-Hartman @ 2020-08-12 7:13 ` Peilin Ye 2020-08-12 8:18 ` Greg Kroah-Hartman 2020-08-12 8:59 ` Dan Carpenter 0 siblings, 2 replies; 10+ messages in thread From: Peilin Ye @ 2020-08-12 7:13 UTC (permalink / raw) To: Greg Kroah-Hartman Cc: linux-fsdevel, syzkaller-bugs, linux-kernel-mentees, linux-kernel On Wed, Aug 12, 2020 at 09:08:27AM +0200, Greg Kroah-Hartman wrote: > On Wed, Aug 12, 2020 at 02:55:56AM -0400, Peilin Ye wrote: > > Prevent hfs_find_init() from dereferencing `tree` as NULL. > > > > Reported-and-tested-by: syzbot+7ca256d0da4af073b2e2@syzkaller.appspotmail.com > > Signed-off-by: Peilin Ye <yepeilin.cs@gmail.com> > > --- > > fs/hfs/bfind.c | 3 +++ > > fs/hfsplus/bfind.c | 3 +++ > > 2 files changed, 6 insertions(+) > > > > diff --git a/fs/hfs/bfind.c b/fs/hfs/bfind.c > > index 4af318fbda77..880b7ea2c0fc 100644 > > --- a/fs/hfs/bfind.c > > +++ b/fs/hfs/bfind.c > > @@ -16,6 +16,9 @@ int hfs_find_init(struct hfs_btree *tree, struct hfs_find_data *fd) > > { > > void *ptr; > > > > + if (!tree) > > + return -EINVAL; > > + > > fd->tree = tree; > > fd->bnode = NULL; > > ptr = kmalloc(tree->max_key_len * 2 + 4, GFP_KERNEL); > > diff --git a/fs/hfsplus/bfind.c b/fs/hfsplus/bfind.c > > index ca2ba8c9f82e..85bef3e44d7a 100644 > > --- a/fs/hfsplus/bfind.c > > +++ b/fs/hfsplus/bfind.c > > @@ -16,6 +16,9 @@ int hfs_find_init(struct hfs_btree *tree, struct hfs_find_data *fd) > > { > > void *ptr; > > > > + if (!tree) > > + return -EINVAL; > > + > > How can tree ever be NULL in these calls? Shouldn't that be fixed as > the root problem here? I see, I will try to figure out what is going on with the reproducer. Thank you, Peilin Ye _______________________________________________ Linux-kernel-mentees mailing list Linux-kernel-mentees@lists.linuxfoundation.org https://lists.linuxfoundation.org/mailman/listinfo/linux-kernel-mentees ^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [Linux-kernel-mentees] [PATCH] hfs, hfsplus: Fix NULL pointer dereference in hfs_find_init() 2020-08-12 7:13 ` Peilin Ye @ 2020-08-12 8:18 ` Greg Kroah-Hartman 2020-08-12 16:33 ` Peilin Ye 2020-08-12 8:59 ` Dan Carpenter 1 sibling, 1 reply; 10+ messages in thread From: Greg Kroah-Hartman @ 2020-08-12 8:18 UTC (permalink / raw) To: Peilin Ye Cc: linux-fsdevel, syzkaller-bugs, linux-kernel-mentees, linux-kernel On Wed, Aug 12, 2020 at 03:13:06AM -0400, Peilin Ye wrote: > On Wed, Aug 12, 2020 at 09:08:27AM +0200, Greg Kroah-Hartman wrote: > > On Wed, Aug 12, 2020 at 02:55:56AM -0400, Peilin Ye wrote: > > > Prevent hfs_find_init() from dereferencing `tree` as NULL. > > > > > > Reported-and-tested-by: syzbot+7ca256d0da4af073b2e2@syzkaller.appspotmail.com > > > Signed-off-by: Peilin Ye <yepeilin.cs@gmail.com> > > > --- > > > fs/hfs/bfind.c | 3 +++ > > > fs/hfsplus/bfind.c | 3 +++ > > > 2 files changed, 6 insertions(+) > > > > > > diff --git a/fs/hfs/bfind.c b/fs/hfs/bfind.c > > > index 4af318fbda77..880b7ea2c0fc 100644 > > > --- a/fs/hfs/bfind.c > > > +++ b/fs/hfs/bfind.c > > > @@ -16,6 +16,9 @@ int hfs_find_init(struct hfs_btree *tree, struct hfs_find_data *fd) > > > { > > > void *ptr; > > > > > > + if (!tree) > > > + return -EINVAL; > > > + > > > fd->tree = tree; > > > fd->bnode = NULL; > > > ptr = kmalloc(tree->max_key_len * 2 + 4, GFP_KERNEL); > > > diff --git a/fs/hfsplus/bfind.c b/fs/hfsplus/bfind.c > > > index ca2ba8c9f82e..85bef3e44d7a 100644 > > > --- a/fs/hfsplus/bfind.c > > > +++ b/fs/hfsplus/bfind.c > > > @@ -16,6 +16,9 @@ int hfs_find_init(struct hfs_btree *tree, struct hfs_find_data *fd) > > > { > > > void *ptr; > > > > > > + if (!tree) > > > + return -EINVAL; > > > + > > > > How can tree ever be NULL in these calls? Shouldn't that be fixed as > > the root problem here? > > I see, I will try to figure out what is going on with the reproducer. That's good to figure out. Note, your patch might be the correct thing to do, as that might be an allowed way to call the function. But in looking at all the callers, they seem to think they have a valid pointer at the moment, so perhaps if this check is added, some other root problem is papered over to be only found later on? thanks, greg k-h _______________________________________________ Linux-kernel-mentees mailing list Linux-kernel-mentees@lists.linuxfoundation.org https://lists.linuxfoundation.org/mailman/listinfo/linux-kernel-mentees ^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [Linux-kernel-mentees] [PATCH] hfs, hfsplus: Fix NULL pointer dereference in hfs_find_init() 2020-08-12 8:18 ` Greg Kroah-Hartman @ 2020-08-12 16:33 ` Peilin Ye 0 siblings, 0 replies; 10+ messages in thread From: Peilin Ye @ 2020-08-12 16:33 UTC (permalink / raw) To: Greg Kroah-Hartman Cc: linux-fsdevel, syzkaller-bugs, linux-kernel-mentees, linux-kernel On Wed, Aug 12, 2020 at 10:18:52AM +0200, Greg Kroah-Hartman wrote: > On Wed, Aug 12, 2020 at 03:13:06AM -0400, Peilin Ye wrote: > > On Wed, Aug 12, 2020 at 09:08:27AM +0200, Greg Kroah-Hartman wrote: > > > On Wed, Aug 12, 2020 at 02:55:56AM -0400, Peilin Ye wrote: > > > > Prevent hfs_find_init() from dereferencing `tree` as NULL. > > > > > > > > Reported-and-tested-by: syzbot+7ca256d0da4af073b2e2@syzkaller.appspotmail.com > > > > Signed-off-by: Peilin Ye <yepeilin.cs@gmail.com> > > > > --- > > > > fs/hfs/bfind.c | 3 +++ > > > > fs/hfsplus/bfind.c | 3 +++ > > > > 2 files changed, 6 insertions(+) > > > > > > > > diff --git a/fs/hfs/bfind.c b/fs/hfs/bfind.c > > > > index 4af318fbda77..880b7ea2c0fc 100644 > > > > --- a/fs/hfs/bfind.c > > > > +++ b/fs/hfs/bfind.c > > > > @@ -16,6 +16,9 @@ int hfs_find_init(struct hfs_btree *tree, struct hfs_find_data *fd) > > > > { > > > > void *ptr; > > > > > > > > + if (!tree) > > > > + return -EINVAL; > > > > + > > > > fd->tree = tree; > > > > fd->bnode = NULL; > > > > ptr = kmalloc(tree->max_key_len * 2 + 4, GFP_KERNEL); > > > > diff --git a/fs/hfsplus/bfind.c b/fs/hfsplus/bfind.c > > > > index ca2ba8c9f82e..85bef3e44d7a 100644 > > > > --- a/fs/hfsplus/bfind.c > > > > +++ b/fs/hfsplus/bfind.c > > > > @@ -16,6 +16,9 @@ int hfs_find_init(struct hfs_btree *tree, struct hfs_find_data *fd) > > > > { > > > > void *ptr; > > > > > > > > + if (!tree) > > > > + return -EINVAL; > > > > + > > > > > > How can tree ever be NULL in these calls? Shouldn't that be fixed as > > > the root problem here? > > > > I see, I will try to figure out what is going on with the reproducer. > > That's good to figure out. Note, your patch might be the correct thing > to do, as that might be an allowed way to call the function. But in > looking at all the callers, they seem to think they have a valid pointer > at the moment, so perhaps if this check is added, some other root > problem is papered over to be only found later on? That's right - Yesterday I noticed that this function has a number of callers who don't check `tree` at all, so I thought maybe we just add the check here...Turned out to be quite the opposite. Thank you, Peilin Ye _______________________________________________ Linux-kernel-mentees mailing list Linux-kernel-mentees@lists.linuxfoundation.org https://lists.linuxfoundation.org/mailman/listinfo/linux-kernel-mentees ^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [Linux-kernel-mentees] [PATCH] hfs, hfsplus: Fix NULL pointer dereference in hfs_find_init() 2020-08-12 7:13 ` Peilin Ye 2020-08-12 8:18 ` Greg Kroah-Hartman @ 2020-08-12 8:59 ` Dan Carpenter 2020-08-12 11:42 ` Big Budsupply ` (2 more replies) 1 sibling, 3 replies; 10+ messages in thread From: Dan Carpenter @ 2020-08-12 8:59 UTC (permalink / raw) To: Peilin Ye Cc: linux-fsdevel, syzkaller-bugs, linux-kernel-mentees, linux-kernel Yeah, the patch doesn't work at all. I looked at one call tree and it is: hfs_mdb_get() tries to allocate HFS_SB(sb)->ext_tree. HFS_SB(sb)->ext_tree = hfs_btree_open(sb, HFS_EXT_CNID, hfs_ext_keycmp); ^^^^^^^^ hfs_btree_open() calls page = read_mapping_page(mapping, 0, NULL); read_mapping_page() calls mapping->a_ops->readpage() which leads to hfs_readpage() which leads to hfs_ext_read_extent() which calls res = hfs_find_init(HFS_SB(inode->i_sb)->ext_tree, &fd); ^^^^^^^^ So we need ->ext_tree to be non-NULL before we can set ->ext_tree to be non-NULL... :/ I wonder how long this has been broken and if we should just delete the AFS file system. regards, dan carpenter _______________________________________________ Linux-kernel-mentees mailing list Linux-kernel-mentees@lists.linuxfoundation.org https://lists.linuxfoundation.org/mailman/listinfo/linux-kernel-mentees ^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [Linux-kernel-mentees] [PATCH] hfs, hfsplus: Fix NULL pointer dereference in hfs_find_init() 2020-08-12 8:59 ` Dan Carpenter @ 2020-08-12 11:42 ` Big Budsupply 2020-08-12 17:23 ` Peilin Ye 2020-08-12 20:24 ` Ernesto A. Fernández 2 siblings, 0 replies; 10+ messages in thread From: Big Budsupply @ 2020-08-12 11:42 UTC (permalink / raw) To: Dan Carpenter Cc: syzkaller-bugs, linux-kernel, linux-fsdevel, linux-kernel-mentees, Peilin Ye [-- Attachment #1.1: Type: text/plain, Size: 1546 bytes --] Hello guys hope you are doing good! we are Bigbudsupply we grow and sell the best medical marijuana product, we are looking for long time customers, you can Email us /Bigbudsupply1@gmail.com Text/+14432672189 Looking forward to working with you guys On Wed, 12 Aug 2020 at 09:59 Dan Carpenter <dan.carpenter@oracle.com> wrote: > Yeah, the patch doesn't work at all. I looked at one call tree and it > > is: > > > > hfs_mdb_get() tries to allocate HFS_SB(sb)->ext_tree. > > > > HFS_SB(sb)->ext_tree = hfs_btree_open(sb, HFS_EXT_CNID, > hfs_ext_keycmp); > > ^^^^^^^^ > > > > hfs_btree_open() calls page = read_mapping_page(mapping, 0, NULL); > > read_mapping_page() calls mapping->a_ops->readpage() which leads to > > hfs_readpage() which leads to hfs_ext_read_extent() which calls > > res = hfs_find_init(HFS_SB(inode->i_sb)->ext_tree, &fd); > > ^^^^^^^^ > > > > So we need ->ext_tree to be non-NULL before we can set ->ext_tree to be > > non-NULL... :/ > > > > I wonder how long this has been broken and if we should just delete the > > AFS file system. > > > > regards, > > dan carpenter > > > > -- > > You received this message because you are subscribed to the Google Groups > "syzkaller-bugs" group. > > To unsubscribe from this group and stop receiving emails from it, send an > email to syzkaller-bugs+unsubscribe@googlegroups.com. > > To view this discussion on the web visit > https://groups.google.com/d/msgid/syzkaller-bugs/20200812085904.GA16441%40kadam > . > > [-- Attachment #1.2: Type: text/html, Size: 2537 bytes --] [-- Attachment #2: Type: text/plain, Size: 201 bytes --] _______________________________________________ Linux-kernel-mentees mailing list Linux-kernel-mentees@lists.linuxfoundation.org https://lists.linuxfoundation.org/mailman/listinfo/linux-kernel-mentees ^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [Linux-kernel-mentees] [PATCH] hfs, hfsplus: Fix NULL pointer dereference in hfs_find_init() 2020-08-12 8:59 ` Dan Carpenter 2020-08-12 11:42 ` Big Budsupply @ 2020-08-12 17:23 ` Peilin Ye 2020-08-12 20:24 ` Ernesto A. Fernández 2 siblings, 0 replies; 10+ messages in thread From: Peilin Ye @ 2020-08-12 17:23 UTC (permalink / raw) To: Dan Carpenter Cc: linux-fsdevel, syzkaller-bugs, linux-kernel-mentees, linux-kernel On Wed, Aug 12, 2020 at 11:59:04AM +0300, Dan Carpenter wrote: > Yeah, the patch doesn't work at all. I looked at one call tree and it > is: > > hfs_mdb_get() tries to allocate HFS_SB(sb)->ext_tree. > > HFS_SB(sb)->ext_tree = hfs_btree_open(sb, HFS_EXT_CNID, hfs_ext_keycmp); > ^^^^^^^^ > > hfs_btree_open() calls page = read_mapping_page(mapping, 0, NULL); > read_mapping_page() calls mapping->a_ops->readpage() which leads to > hfs_readpage() which leads to hfs_ext_read_extent() which calls > res = hfs_find_init(HFS_SB(inode->i_sb)->ext_tree, &fd); > ^^^^^^^^ Thank you for pointing this out! I will try to come up with a better way to fix it. Peilin Ye > So we need ->ext_tree to be non-NULL before we can set ->ext_tree to be > non-NULL... :/ > > I wonder how long this has been broken and if we should just delete the > AFS file system. > > regards, > dan carpenter > _______________________________________________ Linux-kernel-mentees mailing list Linux-kernel-mentees@lists.linuxfoundation.org https://lists.linuxfoundation.org/mailman/listinfo/linux-kernel-mentees ^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [Linux-kernel-mentees] [PATCH] hfs, hfsplus: Fix NULL pointer dereference in hfs_find_init() 2020-08-12 8:59 ` Dan Carpenter 2020-08-12 11:42 ` Big Budsupply 2020-08-12 17:23 ` Peilin Ye @ 2020-08-12 20:24 ` Ernesto A. Fernández 2020-08-12 20:34 ` Ernesto A. Fernández 2 siblings, 1 reply; 10+ messages in thread From: Ernesto A. Fernández @ 2020-08-12 20:24 UTC (permalink / raw) To: Dan Carpenter Cc: syzkaller-bugs, linux-kernel, linux-fsdevel, linux-kernel-mentees, Peilin Ye Hi, On Wed, Aug 12, 2020 at 11:59:04AM +0300, Dan Carpenter wrote: > Yeah, the patch doesn't work at all. I looked at one call tree and it > is: > > hfs_mdb_get() tries to allocate HFS_SB(sb)->ext_tree. > > HFS_SB(sb)->ext_tree = hfs_btree_open(sb, HFS_EXT_CNID, hfs_ext_keycmp); > ^^^^^^^^ > > hfs_btree_open() calls page = read_mapping_page(mapping, 0, NULL); > read_mapping_page() calls mapping->a_ops->readpage() which leads to > hfs_readpage() which leads to hfs_ext_read_extent() which calls > res = hfs_find_init(HFS_SB(inode->i_sb)->ext_tree, &fd); > ^^^^^^^^ > > So we need ->ext_tree to be non-NULL before we can set ->ext_tree to be > non-NULL... :/ For HFS+, the first 8 extents for a file are kept inside its own fork data structure, not in the extent tree. So, in normal operation, you don't need to search the extent tree to find the first page of the extent tree itself. The HFS layout is different, but it should work the same way. Of course this sort of thing can still be triggered by crafted filesystems. If that's what the reproducer is about, I think just returning an error is reasonable. But these modules will never be safe against attacks such as this. > I wonder how long this has been broken and if we should just delete the > AFS file system. > > regards, > dan carpenter _______________________________________________ Linux-kernel-mentees mailing list Linux-kernel-mentees@lists.linuxfoundation.org https://lists.linuxfoundation.org/mailman/listinfo/linux-kernel-mentees ^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [Linux-kernel-mentees] [PATCH] hfs, hfsplus: Fix NULL pointer dereference in hfs_find_init() 2020-08-12 20:24 ` Ernesto A. Fernández @ 2020-08-12 20:34 ` Ernesto A. Fernández 0 siblings, 0 replies; 10+ messages in thread From: Ernesto A. Fernández @ 2020-08-12 20:34 UTC (permalink / raw) To: Dan Carpenter Cc: syzkaller-bugs, linux-kernel, linux-fsdevel, linux-kernel-mentees, Peilin Ye On Wed, Aug 12, 2020 at 05:24:20PM -0300, Ernesto A. Fernández wrote: > If that's what the reproducer is about, I think just returning an error is > reasonable. I guess it would be better to put a check inside hfsplus_inode_read_fork(), to verify that the first extent is always in the right place and wide enough. _______________________________________________ Linux-kernel-mentees mailing list Linux-kernel-mentees@lists.linuxfoundation.org https://lists.linuxfoundation.org/mailman/listinfo/linux-kernel-mentees ^ permalink raw reply [flat|nested] 10+ messages in thread
end of thread, other threads:[~2020-08-12 20:34 UTC | newest] Thread overview: 10+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2020-08-12 6:55 [Linux-kernel-mentees] [PATCH] hfs, hfsplus: Fix NULL pointer dereference in hfs_find_init() Peilin Ye 2020-08-12 7:08 ` Greg Kroah-Hartman 2020-08-12 7:13 ` Peilin Ye 2020-08-12 8:18 ` Greg Kroah-Hartman 2020-08-12 16:33 ` Peilin Ye 2020-08-12 8:59 ` Dan Carpenter 2020-08-12 11:42 ` Big Budsupply 2020-08-12 17:23 ` Peilin Ye 2020-08-12 20:24 ` Ernesto A. Fernández 2020-08-12 20:34 ` Ernesto A. Fernández
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