From fb7a84cac03541f4da18dfa25b3f4767d4efc6fc Mon Sep 17 00:00:00 2001 From: Matt Fleming Date: Fri, 6 May 2016 22:39:29 +0100 Subject: efi/capsule: Move 'capsule' to the stack in efi_capsule_supported() Dan Carpenter reports that passing the address of the pointer to the kmalloc()'d memory for 'capsule' is dangerous: "drivers/firmware/efi/capsule.c:109 efi_capsule_supported() warn: did you mean to pass the address of 'capsule' 108 109 status = efi.query_capsule_caps(&capsule, 1, &max_size, reset); ^^^^^^^^ If we modify capsule inside this function call then at the end of the function we aren't freeing the original pointer that we allocated." Ard Biesheuvel noted that we don't even need to call kmalloc() since the object we allocate isn't very big and doesn't need to persist after the function returns. Place 'capsule' on the stack instead. Suggested-by: Ard Biesheuvel Reported-by: Dan Carpenter Signed-off-by: Matt Fleming Acked-by: Ard Biesheuvel Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Bryan O'Donoghue Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Kweh Hock Leong Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: joeyli Cc: linux-efi@vger.kernel.org Link: http://lkml.kernel.org/r/1462570771-13324-4-git-send-email-matt@codeblueprint.co.uk Signed-off-by: Ingo Molnar --- drivers/firmware/efi/capsule.c | 29 +++++++++++------------------ 1 file changed, 11 insertions(+), 18 deletions(-) diff --git a/drivers/firmware/efi/capsule.c b/drivers/firmware/efi/capsule.c index e530540f368c..53b9fd2293ee 100644 --- a/drivers/firmware/efi/capsule.c +++ b/drivers/firmware/efi/capsule.c @@ -86,33 +86,26 @@ bool efi_capsule_pending(int *reset_type) */ int efi_capsule_supported(efi_guid_t guid, u32 flags, size_t size, int *reset) { - efi_capsule_header_t *capsule; + efi_capsule_header_t capsule; + efi_capsule_header_t *cap_list[] = { &capsule }; efi_status_t status; u64 max_size; - int rv = 0; if (flags & ~EFI_CAPSULE_SUPPORTED_FLAG_MASK) return -EINVAL; - capsule = kmalloc(sizeof(*capsule), GFP_KERNEL); - if (!capsule) - return -ENOMEM; - - capsule->headersize = capsule->imagesize = sizeof(*capsule); - memcpy(&capsule->guid, &guid, sizeof(efi_guid_t)); - capsule->flags = flags; + capsule.headersize = capsule.imagesize = sizeof(capsule); + memcpy(&capsule.guid, &guid, sizeof(efi_guid_t)); + capsule.flags = flags; - status = efi.query_capsule_caps(&capsule, 1, &max_size, reset); - if (status != EFI_SUCCESS) { - rv = efi_status_to_err(status); - goto out; - } + status = efi.query_capsule_caps(cap_list, 1, &max_size, reset); + if (status != EFI_SUCCESS) + return efi_status_to_err(status); if (size > max_size) - rv = -ENOSPC; -out: - kfree(capsule); - return rv; + return -ENOSPC; + + return 0; } EXPORT_SYMBOL_GPL(efi_capsule_supported); -- cgit v1.2.3-70-g09d2