From: Philipp Fent fent@in.tum.de
[ Upstream commit 7a88a6227dc7f2e723bba11ece05e57bd8dce8e4 ]
Commit 9302c1bb8e47 ("efi/libstub: Rewrite file I/O routine") introduced a regression that made a couple of (badly configured) systems fail to boot [1]: Until 5.6, we silently accepted Unix-style file separators in EFI paths, which might violate the EFI standard, but are an easy to make mistake. This fix restores the pre-5.7 behaviour.
[1] https://bbs.archlinux.org/viewtopic.php?id=256273
Fixes: 9302c1bb8e47 ("efi/libstub: Rewrite file I/O routine") Signed-off-by: Philipp Fent fent@in.tum.de Link: https://lore.kernel.org/r/20200615115109.7823-1-fent@in.tum.de [ardb: rewrite as chained if/else statements] Signed-off-by: Ard Biesheuvel ardb@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/firmware/efi/libstub/file.c | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-)
diff --git a/drivers/firmware/efi/libstub/file.c b/drivers/firmware/efi/libstub/file.c index ea66b1f16a79d..f1c4faf58c764 100644 --- a/drivers/firmware/efi/libstub/file.c +++ b/drivers/firmware/efi/libstub/file.c @@ -104,12 +104,20 @@ static int find_file_option(const efi_char16_t *cmdline, int cmdline_len, if (!found) return 0;
+ /* Skip any leading slashes */ + while (cmdline[i] == L'/' || cmdline[i] == L'\') + i++; + while (--result_len > 0 && i < cmdline_len) { - if (cmdline[i] == L'\0' || - cmdline[i] == L'\n' || - cmdline[i] == L' ') + efi_char16_t c = cmdline[i++]; + + if (c == L'\0' || c == L'\n' || c == L' ') break; - *result++ = cmdline[i++]; + else if (c == L'/') + /* Replace UNIX dir separators with EFI standard ones */ + *result++ = L'\'; + else + *result++ = c; } *result = L'\0'; return i;