When a binary is patched or relocated such that the program header table is
moved into a separate PT_LOAD segment (rather than sitting at the start of the
first loadable segment), QEMU's AT_PHDR auxv entry becomes incorrect. The
loader was computing AT_PHDR as load_addr + e_phoff, which assumes the headers
are mapped 1:1 from file offset 0. This breaks when the headers are elsewhere.
The Linux kernel instead locates the PT_LOAD segment that contains e_phoff,
then computes the in-memory address as p_vaddr + (e_phoff - p_offset). This
correctly handles relocated headers.
Fix by:
1. Add phdr_addr field to image_info to cache the resolved address.
2. Initialize to load_addr + e_phoff (fallback for headers outside any PT_LOAD).
3. In the PT_LOAD mapping loop, detect if the segment contains e_phoff and
override with the segment-relative address.
4. Use info->phdr_addr for AT_PHDR instead of the incorrect formula.
Signed-off-by: Akshit Yadav <valium7171@gmail.com>
Reviewed-by: Helge Deller <deller@gmx.de>
(cherry picked from commit 156e536a7b)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
1a212f09df