Commit 4e9d360c authored by Andrii Nakryiko's avatar Andrii Nakryiko Committed by Alexei Starovoitov
Browse files

lib/buildid: remove single-page limit for PHDR search 



Now that freader allows to access multiple pages transparently, there is
no need to limit program headers to the very first ELF file page. Remove
this limitation, but still put some sane limit on amount of program
headers that we are willing to iterate over (set arbitrarily to 256).

Reviewed-by: default avatarEduard Zingerman <eddyz87@gmail.com>
Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20240829174232.3133883-5-andrii@kernel.org


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent d4deb824

lib/buildid.c

+8 −6
Original line number Diff line number Diff line
@@ -8,6 +8,8 @@ 


#define BUILD_ID 3



#define MAX_PHDR_CNT 256



struct freader {

	void *buf;

	u32 buf_sz;
@@ -223,9 +225,9 @@ static int get_build_id_32(struct freader *r, unsigned char *build_id, __u32 *si 
	phnum = READ_ONCE(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;

	/* set upper bound on amount of segments (phdrs) we iterate */

	if (phnum > MAX_PHDR_CNT)

		phnum = MAX_PHDR_CNT;



	/* check that phoff is not large enough to cause an overflow */

	if (phoff + phnum * sizeof(Elf32_Phdr) < phoff)
@@ -260,9 +262,9 @@ static int get_build_id_64(struct freader *r, unsigned char *build_id, __u32 *si 
	phnum = READ_ONCE(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;

	/* set upper bound on amount of segments (phdrs) we iterate */

	if (phnum > MAX_PHDR_CNT)

		phnum = MAX_PHDR_CNT;



	/* check that phoff is not large enough to cause an overflow */

	if (phoff + phnum * sizeof(Elf64_Phdr) < phoff)