From 703bf2d122c95412a30f72658c53ad6292867b0b Mon Sep 17 00:00:00 2001 From: Dave Jones Date: Thu, 5 Apr 2012 14:25:06 -0700 Subject: fs/xattr.c: suppress page allocation failure warnings from sys_listxattr() This size is user controllable, up to a maximum of XATTR_LIST_MAX (64k). So it's trivial for someone to trigger a stream of order:4 page allocation errors. Signed-off-by: Dave Jones Cc: Al Viro Cc: Dave Chinner Acked-by: David Rientjes Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/xattr.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'fs/xattr.c') diff --git a/fs/xattr.c b/fs/xattr.c index d6dfd24..a14d842 100644 --- a/fs/xattr.c +++ b/fs/xattr.c @@ -496,7 +496,7 @@ listxattr(struct dentry *d, char __user *list, size_t size) if (size) { if (size > XATTR_LIST_MAX) size = XATTR_LIST_MAX; - klist = kmalloc(size, GFP_KERNEL); + klist = kmalloc(size, __GFP_NOWARN | GFP_KERNEL); if (!klist) return -ENOMEM; } -- cgit v1.1 From 0d08d7b7e13b5060181b11ecdde82d8fda322123 Mon Sep 17 00:00:00 2001 From: Andrew Morton Date: Thu, 5 Apr 2012 14:25:07 -0700 Subject: fs/xattr.c:listxattr(): fall back to vmalloc() if kmalloc() failed This allocation can be as large as 64k. As David points out, "falling back to vmalloc here is much better solution than failing to retreive the attribute - it will work no matter how fragmented memory gets. That means we don't get incomplete backups occurring after days or months of uptime and successful backups". Cc: Dave Chinner Cc: Dave Jones Cc: David Rientjes Cc: Al Viro Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/xattr.c | 17 +++++++++++++---- 1 file changed, 13 insertions(+), 4 deletions(-) (limited to 'fs/xattr.c') diff --git a/fs/xattr.c b/fs/xattr.c index a14d842..d14afba 100644 --- a/fs/xattr.c +++ b/fs/xattr.c @@ -19,8 +19,9 @@ #include #include #include -#include +#include +#include /* * Check permissions for extended attribute access. This is a bit complicated @@ -492,13 +493,18 @@ listxattr(struct dentry *d, char __user *list, size_t size) { ssize_t error; char *klist = NULL; + char *vlist = NULL; /* If non-NULL, we used vmalloc() */ if (size) { if (size > XATTR_LIST_MAX) size = XATTR_LIST_MAX; klist = kmalloc(size, __GFP_NOWARN | GFP_KERNEL); - if (!klist) - return -ENOMEM; + if (!klist) { + vlist = vmalloc(size); + if (!vlist) + return -ENOMEM; + klist = vlist; + } } error = vfs_listxattr(d, klist, size); @@ -510,7 +516,10 @@ listxattr(struct dentry *d, char __user *list, size_t size) than XATTR_LIST_MAX bytes. Not possible. */ error = -E2BIG; } - kfree(klist); + if (vlist) + vfree(vlist); + else + kfree(klist); return error; } -- cgit v1.1 From 44c824982fd37a578da23cc90885e9690a6a3f0e Mon Sep 17 00:00:00 2001 From: Andrew Morton Date: Thu, 5 Apr 2012 14:25:07 -0700 Subject: fs/xattr.c:setxattr(): improve handling of allocation failures This allocation can be as large as 64k. - Add __GFP_NOWARN so the a falied kmalloc() is silent - Fall back to vmalloc() if the kmalloc() failed Cc: Dave Chinner Cc: Dave Jones Cc: David Rientjes Cc: Al Viro Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/xattr.c | 21 +++++++++++++++++---- 1 file changed, 17 insertions(+), 4 deletions(-) (limited to 'fs/xattr.c') diff --git a/fs/xattr.c b/fs/xattr.c index d14afba..3c8c1cc 100644 --- a/fs/xattr.c +++ b/fs/xattr.c @@ -321,6 +321,7 @@ setxattr(struct dentry *d, const char __user *name, const void __user *value, { int error; void *kvalue = NULL; + void *vvalue = NULL; /* If non-NULL, we used vmalloc() */ char kname[XATTR_NAME_MAX + 1]; if (flags & ~(XATTR_CREATE|XATTR_REPLACE)) @@ -335,13 +336,25 @@ setxattr(struct dentry *d, const char __user *name, const void __user *value, if (size) { if (size > XATTR_SIZE_MAX) return -E2BIG; - kvalue = memdup_user(value, size); - if (IS_ERR(kvalue)) - return PTR_ERR(kvalue); + kvalue = kmalloc(size, GFP_KERNEL | __GFP_NOWARN); + if (!kvalue) { + vvalue = vmalloc(size); + if (!vvalue) + return -ENOMEM; + kvalue = vvalue; + } + if (copy_from_user(kvalue, value, size)) { + error = -EFAULT; + goto out; + } } error = vfs_setxattr(d, kname, kvalue, size, flags); - kfree(kvalue); +out: + if (vvalue) + vfree(vvalue); + else + kfree(kvalue); return error; } -- cgit v1.1