When trying to read an empty binary attribute in configfs, an OOM
message is printed:
vmalloc: allocation failure: 0 bytes
cat: page allocation failure: order:0, mode:0x24000c2
CPU: 1 PID: 1731 Comm: cat Tainted: G W 4.4.0-rc1-koelsch-01576-g480a69c050d4f3ee-dirty #1977
Hardware name: Generic R8A7791 (Flattened Device Tree)
[<c00173a0>] (unwind_backtrace) from [<c0013094>] (show_stack+0x10/0x14)
[<c0013094>] (show_stack) from [<c01f1f38>] (dump_stack+0x70/0x8c)
[<c01f1f38>] (dump_stack) from [<c00b6930>] (warn_alloc_failed+0xe4/0x110)
[<c00b6930>] (warn_alloc_failed) from [<c00dde1c>] (__vmalloc_node_range+0x1cc/0x1f0)
[<c00dde1c>] (__vmalloc_node_range) from [<c00dde88>] (__vmalloc_node+0x48/0x58)
[<c00dde88>] (__vmalloc_node) from [<c00ddec4>] (vmalloc+0x2c/0x3c)
[<c00ddec4>] (vmalloc) from [<c0148304>] (configfs_read_bin_file+0x98/0x118)
[<c0148304>] (configfs_read_bin_file) from [<c00e8a88>] (__vfs_read+0x20/0xcc)
[<c00e8a88>] (__vfs_read) from [<c00e918c>] (vfs_read+0x84/0xec)
[<c00e918c>] (vfs_read) from [<c00e9914>] (SyS_read+0x40/0x80)
Unlike kmalloc(), vmalloc() doesn't support allocating zero bytes.
Hence return early if ops->read_bin_attribute() returns zero.
Signed-off-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
Fixes: 016dd7ff3c56526f ("configfs: Implement binary attributes (v5)")
---
Against
https://github.com/pantoniou/linux-beagle-track-mainline.git/bbb-overlays
How to reproduce:
- mkdir /sys/kernel/config/device-tree/overlays/dummy
- cat /sys/kernel/config/device-tree/overlays/dummy/dtbo
---
fs/configfs/file.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/configfs/file.c b/fs/configfs/file.c
index a3a3c6695fbf1950..20d59bf4737379e3 100644
--- a/fs/configfs/file.c
+++ b/fs/configfs/file.c
@@ -172,7 +172,7 @@ configfs_read_bin_file(struct file *file, char __user *buf,
/* perform first read with buf == NULL to get extent */
len = bin_attr->read(item, NULL, 0);
- if (len < 0) {
+ if (len <= 0) {
retval = len;
goto out;
}
--
1.9.1
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