| Message ID | 20240125145613.12995-1-mora@netapp.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | NFSv4.2: fix nfs4_listxattr kernel BUG at mm/usercopy.c:102 | expand |
On 25 Jan 2024, at 9:56, Jorge Mora wrote: > A call to listxattr() with a buffer size = 0 returns the actual > size of the buffer needed for a subsequent call. When size > 0, > nfs4_listxattr() does not return an error because either > generic_listxattr() or nfs4_listxattr_nfs4_label() consumes > exactly all the bytes then size is 0 when calling > nfs4_listxattr_nfs4_user() which then triggers the following > kernel BUG: > > [ 99.403778] kernel BUG at mm/usercopy.c:102! > [ 99.404063] Internal error: Oops - BUG: 00000000f2000800 [#1] SMP > [ 99.408463] CPU: 0 PID: 3310 Comm: python3 Not tainted 6.6.0-61.fc40.aarch64 #1 > [ 99.415827] Call trace: > [ 99.415985] usercopy_abort+0x70/0xa0 > [ 99.416227] __check_heap_object+0x134/0x158 > [ 99.416505] check_heap_object+0x150/0x188 > [ 99.416696] __check_object_size.part.0+0x78/0x168 > [ 99.416886] __check_object_size+0x28/0x40 > [ 99.417078] listxattr+0x8c/0x120 > [ 99.417252] path_listxattr+0x78/0xe0 > [ 99.417476] __arm64_sys_listxattr+0x28/0x40 > [ 99.417723] invoke_syscall+0x78/0x100 > [ 99.417929] el0_svc_common.constprop.0+0x48/0xf0 > [ 99.418186] do_el0_svc+0x24/0x38 > [ 99.418376] el0_svc+0x3c/0x110 > [ 99.418554] el0t_64_sync_handler+0x120/0x130 > [ 99.418788] el0t_64_sync+0x194/0x198 > [ 99.418994] Code: aa0003e3 d000a3e0 91310000 97f49bdb (d4210000) > > Issue is reproduced when generic_listxattr() returns 'system.nfs4_acl', > thus calling lisxattr() with size = 16 will trigger the bug. > > Add check on nfs4_listxattr() to return ERANGE error when it is > called with size > 0 and the return value is greater than size. > > Fixes: 012a211abd5d ("NFSv4.2: hook in the user extended attribute handlers") > Signed-off-by: Jorge Mora <mora@netapp.com> Reviewed-by: Benjamin Coddington <bcodding@redhat.com> Ben
diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c index 7e3053339d6a..a4704bed5aec 100644 --- a/fs/nfs/nfs4proc.c +++ b/fs/nfs/nfs4proc.c @@ -10615,29 +10615,33 @@ const struct nfs4_minor_version_ops *nfs_v4_minor_ops[] = { static ssize_t nfs4_listxattr(struct dentry *dentry, char *list, size_t size) { ssize_t error, error2, error3; + size_t left = size; - error = generic_listxattr(dentry, list, size); + error = generic_listxattr(dentry, list, left); if (error < 0) return error; if (list) { list += error; - size -= error; + left -= error; } - error2 = nfs4_listxattr_nfs4_label(d_inode(dentry), list, size); + error2 = nfs4_listxattr_nfs4_label(d_inode(dentry), list, left); if (error2 < 0) return error2; if (list) { list += error2; - size -= error2; + left -= error2; } - error3 = nfs4_listxattr_nfs4_user(d_inode(dentry), list, size); + error3 = nfs4_listxattr_nfs4_user(d_inode(dentry), list, left); if (error3 < 0) return error3; - return error + error2 + error3; + error += error2 + error3; + if (size && error > size) + return -ERANGE; + return error; } static void nfs4_enable_swap(struct inode *inode)
A call to listxattr() with a buffer size = 0 returns the actual size of the buffer needed for a subsequent call. When size > 0, nfs4_listxattr() does not return an error because either generic_listxattr() or nfs4_listxattr_nfs4_label() consumes exactly all the bytes then size is 0 when calling nfs4_listxattr_nfs4_user() which then triggers the following kernel BUG: [ 99.403778] kernel BUG at mm/usercopy.c:102! [ 99.404063] Internal error: Oops - BUG: 00000000f2000800 [#1] SMP [ 99.408463] CPU: 0 PID: 3310 Comm: python3 Not tainted 6.6.0-61.fc40.aarch64 #1 [ 99.415827] Call trace: [ 99.415985] usercopy_abort+0x70/0xa0 [ 99.416227] __check_heap_object+0x134/0x158 [ 99.416505] check_heap_object+0x150/0x188 [ 99.416696] __check_object_size.part.0+0x78/0x168 [ 99.416886] __check_object_size+0x28/0x40 [ 99.417078] listxattr+0x8c/0x120 [ 99.417252] path_listxattr+0x78/0xe0 [ 99.417476] __arm64_sys_listxattr+0x28/0x40 [ 99.417723] invoke_syscall+0x78/0x100 [ 99.417929] el0_svc_common.constprop.0+0x48/0xf0 [ 99.418186] do_el0_svc+0x24/0x38 [ 99.418376] el0_svc+0x3c/0x110 [ 99.418554] el0t_64_sync_handler+0x120/0x130 [ 99.418788] el0t_64_sync+0x194/0x198 [ 99.418994] Code: aa0003e3 d000a3e0 91310000 97f49bdb (d4210000) Issue is reproduced when generic_listxattr() returns 'system.nfs4_acl', thus calling lisxattr() with size = 16 will trigger the bug. Add check on nfs4_listxattr() to return ERANGE error when it is called with size > 0 and the return value is greater than size. Fixes: 012a211abd5d ("NFSv4.2: hook in the user extended attribute handlers") Signed-off-by: Jorge Mora <mora@netapp.com> --- fs/nfs/nfs4proc.c | 16 ++++++++++------ 1 file changed, 10 insertions(+), 6 deletions(-)