kevin/linux
1
Fork 0
Code

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

Browse Source 
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: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20240829174232.3133883-5-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Andrii Nakryiko 2024-08-29 10:42:26 -07:00 committed by Alexei Starovoitov
parent d4deb82423
commit 4e9d360c4c
1 changed files with 8 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

14
lib/buildid.c
View File

@ -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)