Clang16 links the purgatory text in two sections:
[ 1] .text PROGBITS 0000000000000000 00000040 00000000000011a1 0000000000000000 AX 0 0 16 [ 2] .rela.text RELA 0000000000000000 00003498 0000000000000648 0000000000000018 I 24 1 8 ... [17] .text.hot. PROGBITS 0000000000000000 00003220 000000000000020b 0000000000000000 AX 0 0 1 [18] .rela.text.hot. RELA 0000000000000000 00004428 0000000000000078 0000000000000018 I 24 17 8
And both of them have their range [sh_addr ... sh_addr+sh_size] on the area pointed by `e_entry`.
This causes that image->start is calculated twice, once for .text and another time for .text.hot. The second calculation leaves image->start in a random location.
Because of this, the system crashes inmediatly after:
kexec_core: Starting new kernel
Cc: stable@vger.kernel.org Reviewed-by: Ross Zwisler zwisler@google.com Signed-off-by: Ricardo Ribalda ribalda@chromium.org --- kernel/kexec_file.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-)
diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c index f1a0e4e3fb5c..25a37d8f113a 100644 --- a/kernel/kexec_file.c +++ b/kernel/kexec_file.c @@ -901,10 +901,21 @@ static int kexec_purgatory_setup_sechdrs(struct purgatory_info *pi, }
offset = ALIGN(offset, align); + + /* + * Check if the segment contains the entry point, if so, + * calculate the value of image->start based on it. + * If the compiler has produced more than one .text sections + * (Eg: .text.hot), they are generally after the main .text + * section, and they shall not be used to calculate + * image->start. So do not re-calculate image->start if it + * is not set to the initial value. + */ if (sechdrs[i].sh_flags & SHF_EXECINSTR && pi->ehdr->e_entry >= sechdrs[i].sh_addr && pi->ehdr->e_entry < (sechdrs[i].sh_addr - + sechdrs[i].sh_size)) { + + sechdrs[i].sh_size) && + kbuf->image->start == pi->ehdr->e_entry) { kbuf->image->start -= sechdrs[i].sh_addr; kbuf->image->start += kbuf->mem + offset; }