On Thu, Jul 25, 2024 at 5:03 AM Jiri Olsa <olsajiri@xxxxxxxxx> wrote: > > On Wed, Jul 24, 2024 at 03:52:02PM -0700, Andrii Nakryiko wrote: > > Current code assumption is that program (segment) headers are following > > ELF header immediately. This is a common case, but is not guaranteed. So > > take into account e_phoff field of the ELF header when accessing program > > headers. > > > > Reported-by: Alexey Dobriyan <adobriyan@xxxxxxxxx> > > Signed-off-by: Andrii Nakryiko <andrii@xxxxxxxxxx> > > looks like this one never got in right? > https://lore.kernel.org/bpf/CAEf4BzaAKAwO=-=0qZQfkHhBodN0MQUHpL-RY7tCHdcFidjv-Q@xxxxxxxxxxxxxx/ > > I couldn't find the place where you remove that check ;-) > yeah, I don't think that landed. And this patch set will supersede that change with a proper support. > jirka > > > --- > > lib/buildid.c | 9 ++++++--- > > 1 file changed, 6 insertions(+), 3 deletions(-) > > > > diff --git a/lib/buildid.c b/lib/buildid.c > > index 1442a2483a8b..ce48ffab4111 100644 > > --- a/lib/buildid.c > > +++ b/lib/buildid.c > > @@ -206,7 +206,7 @@ static int get_build_id_32(struct freader *r, unsigned char *build_id, __u32 *si > > { > > const Elf32_Ehdr *ehdr; > > const Elf32_Phdr *phdr; > > - __u32 phnum, i; > > + __u32 phnum, phoff, i; > > > > ehdr = freader_fetch(r, 0, sizeof(Elf32_Ehdr)); > > if (!ehdr) > > @@ -214,13 +214,14 @@ static int get_build_id_32(struct freader *r, unsigned char *build_id, __u32 *si > > > > /* subsequent freader_fetch() calls invalidate pointers, so remember locally */ > > phnum = ehdr->e_phnum; > > + phoff = READ_ONCE(ehdr->e_phoff); > > > > /* only supports phdr that fits in one page */ > > if (phnum > (PAGE_SIZE - sizeof(Elf32_Ehdr)) / sizeof(Elf32_Phdr)) > > return -EINVAL; > > > > for (i = 0; i < phnum; ++i) { > > - phdr = freader_fetch(r, i * sizeof(Elf32_Phdr), sizeof(Elf32_Phdr)); > > + phdr = freader_fetch(r, phoff + i * sizeof(Elf32_Phdr), sizeof(Elf32_Phdr)); > > if (!phdr) > > return r->err; > > > > @@ -237,6 +238,7 @@ static int get_build_id_64(struct freader *r, unsigned char *build_id, __u32 *si > > const Elf64_Ehdr *ehdr; > > const Elf64_Phdr *phdr; > > __u32 phnum, i; > > + __u64 phoff; > > > > ehdr = freader_fetch(r, 0, sizeof(Elf64_Ehdr)); > > if (!ehdr) > > @@ -244,13 +246,14 @@ static int get_build_id_64(struct freader *r, unsigned char *build_id, __u32 *si > > > > /* subsequent freader_fetch() calls invalidate pointers, so remember locally */ > > phnum = ehdr->e_phnum; > > + phoff = READ_ONCE(ehdr->e_phoff); > > > > /* only supports phdr that fits in one page */ > > if (phnum > (PAGE_SIZE - sizeof(Elf64_Ehdr)) / sizeof(Elf64_Phdr)) > > return -EINVAL; > > > > for (i = 0; i < phnum; ++i) { > > - phdr = freader_fetch(r, i * sizeof(Elf64_Phdr), sizeof(Elf64_Phdr)); > > + phdr = freader_fetch(r, phoff + i * sizeof(Elf64_Phdr), sizeof(Elf64_Phdr)); > > if (!phdr) > > return r->err; > > > > -- > > 2.43.0 > > > >
