[PATCH V2] efi_loader: loosen buffer parameter check in efi_file_read_int

Peng Fan (OSS) peng.fan at oss.nxp.com
Wed Apr 28 15:54:01 CEST 2021

From: Peng Fan <peng.fan at nxp.com>

This is same issue as https://bugzilla.redhat.com/show_bug.cgi?id=1733817,
but that fix was wrongly partial reverted.

When reading a directory, EFI_BUFFER_TOO_SMALL should be returned when
the supplied buffer is too small, so a use-case is to call
EFI_FILE_PROTOCOL.Read() with *buffer_size=0 and buffer=NULL to
obtain the needed size before doing the actual read.

So remove the check only for directory reading, file reading already
do the check by itself.

Fixes: db12f518edb0("efi_loader: implement non-blocking file services")
Cc: Heinrich Schuchardt <xypron.glpk at gmx.de>
Cc: Stefan Sørensen <stefan.sorensen at spectralink.com>
Tested-by: Peter Robinson <pbrobinson at gmail.com>
Signed-off-by: Peng Fan <peng.fan at nxp.com>

 Update commit log Per Heinrich's comments.
 Add T-b tag

 lib/efi_loader/efi_file.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/efi_loader/efi_file.c b/lib/efi_loader/efi_file.c
index 204105e25a..6b3f5962be 100644
--- a/lib/efi_loader/efi_file.c
+++ b/lib/efi_loader/efi_file.c
@@ -554,7 +554,7 @@ static efi_status_t efi_file_read_int(struct efi_file_handle *this,
 	efi_status_t ret = EFI_SUCCESS;
 	u64 bs;
-	if (!this || !buffer_size || !buffer)
+	if (!this || !buffer_size)
 	bs = *buffer_size;

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