On Fri, 2013-01-25 at 00:25 +0000, Al Viro wrote: > 1) process A does write() on efivars file, reaches ->get_variable(), > gets newdatasize set, drops efivars->lock and loses CPU before an attempt to > grab ->i_mutex. process B comes and does the same thing, replacing the > variable contents. Then it grabs ->i_mutex, updates size, drops ->i_mutex > and buggers off. At which point A gets CPU back and proceeds to set size > to whatever would be valid for its write. Only the value is bogus now... Crap, yes. We'll have to jiggle the locking rules around to fix this one. > 2) what's to prevent EFI_NOT_FOUND being hit twice? Bad things > will obviously happen in that case... I'm not sure which execution path will trigger this? Oh, if we're spinning for the spinlock in efivarfs_unlink() while another process does a delete via efivarfs_file_write()? Yeah, that's gonna cause some tears. Thanks, Al. -- To unsubscribe from this list: send the line "unsubscribe linux-efi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
